Sportsboard structures

ABSTRACT

A sports board that includes an elongate, water impervious, thermoplastic foam core having an upper surface and an under surface; an upper layer covering at least a portion of the upper surface; and an under layer covering at least a portion of the under surface. The foam core is made of a foamed material having a water absorption (measured according to ASTM C-272) of less than 2 volume percent.

REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority of U.S. ProvisionalApplication Ser. No. 60/920,073 filed Mar. 26, 2007 entitled“Sportsboard Structures,” which is herein incorporated by reference inits entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is directed to novel sports boards that can beused for various sporting activities.

2. Description of the Prior Art

Boards and modified boards have been used for various sports and/orathletic activities such as for example surfing, riding waves, sailboarding, being towed by a boat, water skiing, snow boarding, sledding,snow skiing, and skateboarding.

Surfboards are flat or slightly curved narrow floating bodies which aresuitable for use for one or more individuals to move along with or ridea swell or wave of water as it approaches land, a shoreline or a beach.

Sailboards can be similar to surfboards, but can be fitted with a sail,which catches available wind currents to propel the board, thus notrelying solely on available water currents and/or waves to provide theimpetus for forward motion.

Often, in order to stabilize the direction, surfboards and sailboardsrequire a fin, i.e., a plate of triangular design, and whose plane isarranged essentially parallel to the plane of the direction of travel.

Surfboards and sailboards are generally made of wood, or a plasticmaterial, for example, epoxy resin, acrylonitrile-butadiene-styrene(ABS) resin or similar materials, which form the actual rump or body andsurround a core made of foamed material, such as polystyrene orpolyurethane. Since, for various reasons, the boards have to be designedto be as light as possible, the actual plastic skin is not very thick.

U.S. Pat. No. 5,928,045 discloses a sports board having a foam core, anda deck layer, a bottom layer and an outer rail, which cover the foamcore.

U.S. Pat. No. 3,337,886 discloses a surfboard having a core of foammaterial and an outer skin or shell.

GB 961,612 discloses surfboards composed of an expanded polystyreneplate with a plastic cover. The polystyrene material used for thissurfboard is “water repellent”. The expanded polystyrene plate iscovered with plastic. Although this combination provides a surfboardwith water repellent characteristics and an external surface to supportthe users, the combination is not impact resistant.

EP 224 023 discloses a surfboard having a compound structure where thefoaming core is covered with a synthetic resin and a thermoplasticmaterial with a silver braid tissue sandwiched in-between. The silverbraid tissue provides a more rigid foam structure.

FR 2 787 088 discloses a sandwich-type structure for a surfboard. Thissurfboard includes a soft foam core such as polystyrene and polyurethanebetween fiberglass and carbon. The structure is mounted with an adhesivesubstance such as epoxy resin and laminated polymers.

U.S. Pat. No. 5,275,860 discloses surf boards and body boards where theboard includes a core foam which is a closed pore or closed cell foam towhich is directly bonded an upper and lower skin. To achieve asubstantially high integrity bond, an intermediate layer is composed ofa mixture of the polymeric material of the foam and the differentpolymeric material of the skins. The foam is a polypropylene expandedbead foam while the skins are high density polyethylene.

U.S. Pat. No. 5,944,570 discloses a surfboard which has a prestressedcenter stringer with a foam core element located on each side of thestringer to form a center core element.

U.S. Pat. No. 4,798,549 discloses a surfboard that includes an elongatedstringer with upper and lower surfaces curved generally to thelongitudinal profile of the surfboard, a passage formed into andextending along the length of the stringer, outlet ports spaced alongthe stringer, a fin box formed in the stringer at the rear end thereof.The passage, ports, and fin box are constructed and arranged for theintroduction of at least one of foam and steam therethrough forintroduction into a space adjacent to said stringer.

U.S. Pat. No. 4,850,913 discloses a sports board for surfing, snowsledding, and other sports that has a shaped polyethylene foam core towhich a polyethylene film/polyethylene foam sheet laminate is heatlaminated over substantially all the surfaces of the core.

U.S. Pat. No. 4,887,986 discloses surfboards and sail boards thatinclude an inflexible floating body having a stern and a prow; twoflexible side portions attached to the inflexible floating body, one oneither side thereof; and a mast foot located on the inflexible floatingbody, where the flexible side portions are incorporated into theflexible floating body from the stern to about the range of the mastfoot and the inflexible floating body tapers between the flexible sideportions in the direction of the stern to become a narrow bridge that isnarrower than each of the flexible side portions.

U.S. Pat. No. 6,712,657 discloses body boards and surfboards having aspine member longitudinally mounted between the two halves of the board.Reinforcement members are mounted longitudinally and transversally alongthe board blanks.

U.S. Patent Application Publication 2006/0270288 discloses a process ofwrapping a foam core surfboard shape with ¼″ slick foam skins via heattransfer. The heat transferred “foam stacked rail configurations” allow“pinstripes” to outline the outer edges of the board.

A body board is used by a rider to maneuver on ocean waves. The ridertypically holds one or both side rails of the body board while therider's hips, chest, knee, and/or foot are positioned on the top deck ofthe body board. The combination of ocean surf, the rider's weight, andthe rider's directing the body board with the hands, elbows, torso, kneeand/or foot places enormous flex and torsion stress on the body board.The flex and torsion stress tend to distort the body board, andgenerally this is an undesirable result because successful completion ofmaneuvers requires the body board's responding adequately to the rider'ssteering. Force applied to the body board that only distorts the boarddoes not help the rider in redirecting the board. Thus, a high degree ofstiffness of the body board is desirable.

On the other hand, simply making the body board to be very rigid is nota practicable solution because of weight concerns and because flex inthe body board may be desirable along certain sections of the board. Forexample, it may be desirable for the board to be more flexible at atransverse line about a quarter of the way aft of the nose and leadcorners. Such flexibility allows the rider to pull up the nose,distorting it above the plane of the main deck of the body board to keepthe nose and lead corners from dropping under the water's surface in adynamic situation where the nose is being forced downwardly. However, inthe forward quarter of the board, it is generally considered desirablefor the board to be very stiff along a transverse line so that therider's steering inputs on one side of the board will effectively betransmitted to the opposite side of the board and redirect the oppositeside. Notwithstanding these generalizations, variations in individualriders' styles and preferences for body board performancecharacteristics, as well as wide variations in surf conditions,complicate the task of providing appropriate stiffening to a body board.

In general, body boards can include a variable flexure characteristic,e.g., needed flexure in the nose area for what is known as “power turns”and strength in the mid and tail sections, which may be required forspeed. The nose section can be configured to permit corner flexing orflexing along the entire nose section. In general, the bottom skin issmooth, tough and scratch resistant for speed over the water. The deckskin or upper surface of the board is textured to provide relative slipresistance.

In addition to the above, there is a characteristic of a body boardknown as “rocker”. This generally refers to the bending up from thecenterline of the body board. There is overall rocker, nose rocker andtail rocker. Rocker usually affects the ability of the board to planeabove the uneven surface of the water. There is no “perfect” rocker butthere is general agreement on what constitutes a good rocker. Typicallya good rocker involves a gentle curve upward from about ⅓ back from thenose with a resulting rise from the bottom of the board to about 1½inches at the nose. The other ⅔ of the board should be flat or have avery small amount of rise from about ⅓ back from the nose.

Body boards are typically constructed of a buoyant foam core to whichare attached an upper skin, a lower skin, and side rails. The addedskins and rails provide durable outer surfaces, and the lower skintypically has a slick outer surface to speed the board on the water.

U.S. Patent Application Publication 2003/0008575 discloses a body boardthat includes a foam core with buoyancy to support a rider in water. Asubstantially solid and rigid, generally planar stiffening element iscoupled to the core, for example by embedding therein, and the elementprovides a resistance to flexing in response to the rider's applying abending force to the core. The stiffening element can include a beamoriented in a direction generally perpendicular to the longitudinal axisof the core, a beam oriented in a direction generally parallel to thelongitudinal axis, and/or a beam oriented in a direction oblique to thelongitudinal axis. The resistance to flexing provided by the stiffeningelement may increase in a continuously varying amount over at least aportion of the foam core. The element may provide the resistance along afirst selected vector and a second selected vector, wherein the secondselected vector is not parallel to the first.

A sled board is a sliding device that includes an elongate memberconfigured to slide on any sufficiently downward sloping, slipperysurface, such as snow, ice, grass, metal, or water on a water slide withone or more riders in a sitting, kneeling, or prone position.

U.S. Patent Application Publications 2003/0205872 and 2005/0035564disclose a soft foam sled board prepared from a shaped polyethylene foamcore, and at least the bottom surface of the core is covered by a slick,polyethylene film/polyethylene foam sheet laminate which provides littlefrictional resistance between the sled board and sliding surface.

A snow board is a sliding device that includes an elongate memberconfigured to slide on a snow-covered downward sloping surface with oneor more riders in a standing position.

U.S. Pat. No. 5,865,446 discloses a snow board that includes a firstsection having an upper surface, a lower surface, an outer end and aninner end, the outer end being upwardly curved to facilitate movement ofthe first section over a surface in a first direction; a second sectionhaving an upper surface, a lower surface, an outer end and an inner end,the outer end being upwardly curved to facilitate movement of the secondsection over the surface in a second direction; a flexible connector forconnecting the inner end of the first section to the inner end of thesecond section, the flexible connector being capable of twisting andbeing flexible in both a horizontal and vertical direction; a firstbinding for securing one of the user's feet to the upper surface of thefirst section, the first binding being fixedly secured to the firstsection: and a second binding for securing the other foot of the user tothe upper surface of the second section, the second binding beingfixedly secured to the second section; whereby the user is able tofacilitate the movement of the snow board in either the first or thesecond direction. The first and second sections of the snow board caneach have a mid section positioned between the inner and outer ends andthe mid-sections can be constructed from foam core or solid polymerresins.

A skateboard is a narrow elongated wheeled platform adapted for a riderto be transported in a standing position.

U.S. Pat. No. 5,716,562 discloses a method for making an injectionmolded, foamed, composite material skateboard. The skateboard body isformed of a composite material including a foamed structural plasticmass including plural, elongate strands of carbon fiber materialdistributed within the confines of the mass. The skateboard body isformed by injection molding using a thermoplastic such as nylon,polypropylene and polyethylene.

Sports boards that are lightweight are advantageous, as in most cases,it is desirable that the rider not have to carry any more weight thannecessary. Additionally, in water applications, the weight of the boardcan adversely affect the buoyancy of the board.

Unfortunately, foam core boards utilizing polyurethane, expandedpolystyrene, and/or expanded polypropylene tend to take on moisture whenexposed to water making them heavier and less desirable.

Additionally, in many applications for sports boards, it is desirablefor the board to have good flexibility, the ability of a board to“spring” back to its original shape when deformed. Flexibility canprovide, for example, acceleration when surfing and improved turningradius and acceleration when snowboarding.

Though flexibility is a desirable attribute, it has proved elusive tobuild into a sports board, and typically requires time consuming andexpensive construction methods.

Thus, there is a need in the art for sports boards that are light inweight, that do not take on water and that can provide good flexibilitycharacteristics in an economical fashion.

SUMMARY OF THE INVENTION

The present invention provides a sports board that includes an elongate,water impervious, thermoplastic foam core having an upper surface and anunder surface; an upper layer covering at least a portion of the uppersurface; and an under layer covering at least a portion of the undersurface. The foam core is made of a foamed material having a waterabsorption (measured according to ASTM C-272) of less than 2 volumepercent volume percent.

The present invention also provides a surfboard that includes anelongate, water impervious, foam core comprising an interpenetratingnetwork of one or more polyolefins and one or more polymers of vinylaromatic monomers having and upper surface and an under surface; anupper layer covering at least a portion of the upper surface; and anunder layer covering at least a portion of the under surface. The foamcore is made of a foamed material having a water absorption (measuredaccording to ASTM C-272) of less than 2 volume percent volume percent.

A surfboard blank that includes an elongate, water resistant, firstportion comprising an expandable polymer matrix having an inner edge, alead end and a tail end; an elongate, water resistant, second portioncomprising an expandable polymer matrix having an inner edge, a lead endand a tail end; and a stringer disposed along and between the inneredges of the first portion and the second portion and secured thereto.The expandable polymer matrix contains one or more resins selected frominterpolymers of a polyolefin and in situ polymerized vinyl aromaticmonomers, rubber modified polystyrene, polyolefins, polystyrene modifiedrubber, polyphenylene oxide, and combinations and blends thereof.

DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a top plan view of a surfboard according to embodiments ofinvention;

FIG. 2 shows a bottom plan view of a surfboard according to embodimentsof the invention;

FIG. 3 shows a side elevation view of a surfboard according toembodiments of the invention;

FIG. 4 shows a cross sectional view of a surfboard according toembodiments of the invention;

FIG. 5 shows a cross sectional view of a surfboard according toembodiments of the invention;

FIG. 6 shows a top plan view of a surfboard according to embodiments ofthe invention;

FIG. 7 shows a bottom plan view of a surfboard according to embodimentsof the invention;

FIG. 8 shows a side elevation view of a surfboard according toembodiments of the invention;

FIG. 9 shows a cross sectional view of a surfboard according toembodiments of the invention;

FIG. 10 shows a cross sectional view of a surfboard according toembodiments of the invention;

FIG. 11 is a top plan view of a body board according to embodiments ofthe invention;

FIG. 12 is a side elevation view of a body board according toembodiments of the invention;

FIG. 13 is a cross-sectional view of a body board according toembodiments of the invention;

FIG. 14 is a cross-sectional view of a body board according toembodiments of the invention;

FIG. 15 is a top plan view of a water ski according to embodiments ofthe invention;

FIG. 16 is a side elevation view of a water ski according to embodimentsof the invention;

FIG. 17 is a cross-sectional view of a water ski according toembodiments of the invention;

FIG. 18 is a cross-sectional view of a water ski according toembodiments of the invention;

FIG. 19 is a top plan view of a snowboard according to embodiments ofthe invention;

FIG. 20 is a side elevation view of a snowboard according to embodimentsof the invention;

FIG. 21 is a cross-sectional view of a snowboard according toembodiments of the invention;

FIG. 22 is a cross-sectional view of a snowboard according toembodiments of the invention;

FIG. 23 is a top plan view of a snow ski according to embodiments of theinvention;

FIG. 24 is a side elevation view of a snow ski according to embodimentsof the invention;

FIG. 25 is a cross-sectional view of a snow ski according to embodimentsof the invention;

FIG. 26 is a cross-sectional view of a snow ski according to embodimentsof the invention;

FIG. 27 is a top plan view of a sled according to embodiments of theinvention;

FIG. 28 is a bottom plan view of a sled according to embodiments of theinvention;

FIG. 29 is a side elevation view of a sled according to embodiments ofthe invention;

FIG. 30 is a cross-sectional view of a sled according to embodiments ofthe invention;

FIG. 31 is a top plan view of a surfboard blank according to embodimentsof the invention;

FIG. 32 is a side elevation view of the surfboard blank of FIG. 31;

FIG. 33 is a top plan view of a surfboard blank according to embodimentsof the invention;

FIG. 34 is a side elevation view of the surfboard blank of FIG. 33;

FIG. 35 is a top plan view of a surfboard blank according to embodimentsof the invention; and

FIG. 36 is a side elevation view of the surfboard blank of FIG. 35.

DETAILED DESCRIPTION OF THE INVENTION

For the purpose of the description hereinafter, the terms “upper”,“lower”, “inner”, “outer”, “right”, “left”, “vertical”, “horizontal”,“top”, “bottom”, and derivatives thereof, shall relate to the inventionas oriented in the drawing Figures. However, it is to be understood thatthe invention may assume alternate variations and step sequences exceptwhere expressly specified to the contrary. It is also to be understoodthat the specific devices and processes, illustrated in the attacheddrawings and described in the following specification, is an exemplaryembodiment of the present invention. Hence, specific dimensions andother physical characteristics related to the embodiment disclosedherein are not to be considered as limiting the invention. In describingthe embodiments of the present invention, reference will be made hereinto the drawings in which like numerals refer to like features of theinvention.

Other than in the operating examples or where otherwise indicated, allnumbers or expressions referring to quantities of ingredients, reactionconditions, etc. used in the specification and claims are to beunderstood as modified in all instances by the term “about”.Accordingly, unless indicated to the contrary, the numerical parametersset forth in the following specification and attached claims areapproximations that can vary depending upon the desired properties,which the present invention desires to obtain. At the very least, andnot as an attempt to limit the application of the doctrine ofequivalents to the scope of the claims, each numerical parameter shouldat least be construed in light of the number of reported significantdigits and by applying ordinary rounding techniques.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the invention are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical values, however, inherently contain certainerrors necessarily resulting from the standard deviation found in theirrespective testing measurements.

Also, it should be understood that any numerical range recited herein isintended to include all sub-ranges subsumed therein. For example, arange of “1 to 10” is intended to include all sub-ranges between andincluding the recited minimum value of 1 and the recited maximum valueof 10; that is, having a minimum value equal to or greater than 1 and amaximum value of equal to or less than 10. Because the disclosednumerical ranges are continuous, they include every value between theminimum and maximum values. Unless expressly indicated otherwise, thevarious numerical ranges specified in this application areapproximations.

As used herein the term “surfboard” refers to an elongate memberconfigured to float, which is suitable for one or more riders to use ina standing position to surf.

As used herein, the term “sailboard” refers to an elongate memberconfigured to float, which is or can be fitted with a sail and issuitable for one or more riders to use in a standing position towindsurf and the like.

As used herein the term “body board” refers to an elongate memberconfigured to float, which is used by a rider to maneuver on ocean wavesin a sitting, kneeling or prone position.

As used herein the term “wave board” refers to a small roughlyrectangular member configured to float, which is used by a rider tomaneuver on ocean waves in a prone position.

As used herein the term “sled board” refers to a sliding device thatincludes an elongate member configured to slide on any sufficientlydownward sloping slippery surface, such as snow, ice, grass, metal, orwater on a water slide with one or more riders in a sitting, kneeling,or prone position.

As used herein the term “snow board” refers to a sliding device thatincludes an elongate member configured to slide on a snow-covereddownward sloping surface with one or more riders in a standing position.

As used herein the term “skateboard” refers to a narrow elongatedwheeled platform adapted for one or more riders to be transported in astanding position.

As used herein the term “snow ski” refers to a narrow, generallyrectangular sliding device used in pairs to slide on a snow-covereddownward sloping surface with a rider in a standing position with onefoot secured to each device.

As used herein the term “water ski” refers to a narrow generallyrectangular sliding device that can optionally be used in pairs, toglide along the surface of water while being pulled by a motorized watercraft with a rider in a standing position with feet secured to one ortwo of such devices.

As used herein the term “go-kart” refers to a rectangular wheeledplatform adapted for one or more riders to be transported in a sitting,kneeling, or prone position.

As used herein, the term “expandable polymer matrix” refers to apolymeric material in particulate or bead form that is impregnated witha blowing agent such that when the particulates and/or beads are exposedto heat, evaporation of the blowing agent (as described below) effectsthe formation of a cellular structure and/or an expanding cellularstructure in the particulates and/or beads causing the bead to expandand when the expanded beads are placed in a mold and further exposed toheat, the beads can further expand and the outer surfaces of theparticulates and/or beads can fuse together to form a continuous mass ofpolymeric material conforming to the shape of the mold.

As used herein, the terms “expanded plastics”, “prepuff”, “expandedresin beads” and “prefoam” refer to foamed thermoplastic particles thathave been impregnated with a blowing agent, at least some of which hasbeen subsequently removed (as a non-limiting example heated and expandedfollowed by evaporation and diffusion out of the bead) in a way thatincreases the volume of the particles and accordingly decreases theirbulk density.

As used herein, the term “thermoplastic” refers to materials that arecapable of softening, fusing, and/or modifying their shape when heatedand of hardening again when cooled.

As used herein, the term “polymer” is meant to encompass, withoutlimitation, homopolymers, copolymers and graft copolymers.

As used herein, the term “polyolefin” refers to a polymer prepared fromat least one olefinic monomer, such as alpha unsaturated C₂-C₃₂ linearor branched alkenes, non-limiting examples of which include ethylene,propylene, 1-butene, 1-hexene and 1-octene.

As used herein, the term “polyethylene” refers to and includes not onlya homopolymer of ethylene, but also an ethylene copolymer containingunits of at least 50 mole %, in some cases at least 70 mole %, and inother cases at least 80 mole % of an ethylene unit and a correspondingproportion of units from a monomer copolymerizable with ethylene, andblends containing at least 50% by weight, in some cases at least 60% byweight, and in other cases at least 75% by weight of an ethylenehomopolymer or copolymer with another polymer.

Non-limiting examples of monomers that can be copolymerized withethylene include vinyl acetate, vinyl chloride, propylene, 1-butene,1-hexene, 1-octene, and (meth)acrylic acid and its esters.

Polymers that can be blended with ethylene homopolymers or copolymersinclude any polymer compatible with ethylene homopolymers or copolymers.Non-limiting examples of polymers that can be blended with ethylenehomopolymers or copolymers include polypropylene, polybutadiene,polyisoprene, polychloroprene, chlorinated polyethylene, polyvinylchloride, styrene/butadiene copolymers, vinyl acetate/ethylenecopolymers, styrenic polymers, acrylonitrile/butadiene copolymers,styrene/butadiene/acrylonitrile copolymers, and vinyl chloride/vinylacetate copolymer.

As used herein, the term “styrenic polymers” refers to homopolymers ofstyrenic monomers and copolymers of styrenic monomers and anothercopolymerizable monomer, where the styrenic monomers make up at least 50mole percent of the monomeric units in the copolymer. Non-limitingexamples of styrenic monomers include styrene, p-methyl styrene,α-methyl styrene, tertiary butyl styrene, dimethyl styrene,dibromostyrene, nuclear brominated or chlorinated derivatives thereofand combinations thereof. Non-limiting examples of suitablecopolymerizable monomers include 1,3-butadiene, C₁-C₃₂ linear, cyclic orbranched alkyl (meth)acrylates (specific non-limiting examples includebutyl (meth)acrylate, ethyl (meth)acrylate, methyl (meth)acrylate, and2-ethylhexyl (meth)acrylate), butyl acrylate, acrylonitrile, vinylacetate, alpha-methylethylene, divinyl benzene, maleic anhydride, maleicacid, fumaric acid, C₁-C₁₂ linear, branched or cyclic mono- and di-alkylesters of maleic acid, C₁-C₁₂ linear, branched or cyclic mono- anddi-alkyl esters of fumaric acid, itaconic acid, C₁-C₁₂ linear, branchedor cyclic mono- and di-alkyl esters of itaconic acid, itaconic anhydrideand combinations thereof.

As used herein, the terms “(meth)acrylic” and “(meth)acrylate” are meantto include both acrylic and methacrylic acid derivatives, such as thecorresponding alkyl esters often referred to as acrylates and(meth)acrylates, which the term “(meth)acrylate” is meant to encompass.

As used herein, the term “molding” refers to the shaping of a pliablematerial to assume a new desired shape. Molding can involve the use ofspecific molding tools such as male and female molding tools, sculpturedplatens, and the like. It can also include the use of specificallyshaped core members including compressible core members that are used toimpart a desired shape to at least a portion of a thermoplasticmaterial.

As used herein, the term “rubber” refers to natural or syntheticpolymeric substances which have the ability to undergo deformation underthe influence of a force and regain their original shape once the forceis removed.

As used herein, the term “rubber modified polystyrene” refers tostyrenic polymers where the styrenic polymer constitutes a continuousphase and the rubber constitutes a dispersed phase in the resin.

As used herein, the term “polystyrene modified rubber” refers to resinswhere the rubber constitutes a continuous phase and the styrenic polymerconstitutes a dispersed phase in the resin as described in copendingU.S. Patent Publication No. 2006-0276558 A1, the relevant portions ofwhich are herein incorporated by reference.

The present invention provides a sports board that includes an elongate,water resistant or impervious, thermoplastic foam core having and uppersurface and an under surface; an upper layer covering at least a portionof the upper surface; and an under layer covering at least a portion ofthe under surface.

The thermoplastic foam core contains a foamed expandable polymer matrixthat is at least resistant or impervious to water. The expandablepolymer matrix contains one or more thermoplastic resins. Suitablethermoplastic resins include, but are not limited to an interpolymers ofa polyolefin and in situ polymerized vinyl aromatic monomers, rubbermodified polystyrene, polystyrene modified rubber, polyphenylene oxide,blends of polyolefins and at least one other polymer, and combinationsand blends thereof.

The thermoplastic resins can be in the form of beads, pellets, granules,or other particles convenient for use in expansion and moldingoperations.

In an embodiment of the invention, the thermoplastic resins indicatedabove can be blended with and can include one or more polymers selectedfrom homopolymers of vinyl aromatic monomers; copolymers of at least onevinyl aromatic monomer with one or more of divinylbenzene, conjugateddienes, alkyl methacrylates, alkyl acrylates, acrylonitrile, and/ormaleic anhydride; polyolefins; polycarbonates; polyesters; polyamides;natural rubbers; synthetic rubbers; and combinations thereof.

In an particular embodiment of the invention, the thermoplastic resinsindicated above is a blend of one or more polyolefins and one or morepolymers selected from homopolymers of vinyl aromatic monomers;copolymers of at least one vinyl aromatic monomer with one or more ofdivinylbenzene, conjugated dienes, alkyl methacrylates, alkyl acrylates,acrylonitrile, and/or maleic anhydride; polycarbonates; polyesters;polyamides; natural rubbers; synthetic rubbers; and combinationsthereof.

In a particular aspects of this embodiment of the invention, theexpandable thermoplastics can include thermoplastic homopolymers orcopolymers selected from homopolymers derived from vinyl aromaticmonomers including styrene, isopropylstyrene, alpha-methylstyrene,nuclear methylstyrenes, chlorostyrene, tert-butylstyrene, and the like,as well as copolymers prepared by the copolymerization of at least onevinyl aromatic monomer as described above with one or more othermonomers, non-limiting examples being divinylbenzene, conjugated dienes(non-limiting examples being butadiene, isoprene, 1,3- and2,4-hexadiene), alkyl methacrylates, alkyl acrylates, acrylonitrile, andmaleic anhydride, wherein the vinyl aromatic monomer is present in atleast 50% by weight of the copolymer. In an embodiment of the invention,styrenic polymers are used, particularly polystyrene. However, othersuitable polymers can be included, such as polyolefins (e.g.,polyethylene, polypropylene), polycarbonates, polyphenylene oxides, andmixtures thereof. In embodiments of the invention, mixtures of theabove-mentioned polymers can be used.

As indicated above, the expandable polymer matrix can include aninterpolymer of a polyolefin and in situ polymerized vinyl aromaticmonomers and optionally other expandable polymers.

In embodiments of the invention, the interpolymer of a polyolefin and insitu polymerized vinyl aromatic monomers can be one or more of thosedescribed in U.S. Pat. Nos. 3,959,189; 4,168,353; 4,303,756, 4,303,757and 6,908,949, the relevant portions of which are herein incorporated byreference. A non-limiting example of such interpolymers that can be usedin the present invention include those available under the trade nameARCEL®, available from NOVA Chemicals Inc., Pittsburgh, Pa. andPIOCELAN®, available from Sekisui Plastics Co., Ltd., Tokyo, Japan.

In embodiments of the invention, the interpolymer of a polyolefin and insitu polymerized vinyl aromatic monomers is a particle or resin bead,which is subsequently processed to form the foam core of a sports boardaccording to the present invention. The interpolymer particles used inthe invention include a polyolefin and an in situ polymerized vinylaromatic resin that form an interpenetrating network of polyolefin andvinyl aromatic resin particles. The interpolymer particles areimpregnated with a blowing agent and optionally, a plasticizer.

Such interpolymer particles can be obtained by processes that includesuspending polyolefin particles and vinyl aromatic monomer or monomermixtures in an aqueous suspension and polymerizing the monomer ormonomer mixtures inside the polyolefin particles. Non-limiting examplesof such processes are disclosed in U.S. Pat. Nos. 3,959,189, 4,168,353and 6,908,949.

In an embodiment of the invention, the polyolefin can include one ormore polyethylene resins selected from low-, medium-, and high-densitypolyethylene; an ethylene vinyl acetate copolymer; an ethylene/propylenecopolymer; a blend of polyethylene and polypropylene; a blend ofpolyethylene and an ethylene/vinyl acetate copolymer; and a blend ofpolyethylene and an ethylene/propylene copolymer. Ethylene-butylacrylate copolymer and ethylene-methyl methacrylate copolymer can alsobe used.

As indicated above, the thermoplastic resin of the polymer matrix caninclude a polystyrene modified rubber where the rubber constitutes acontinuous phase and the styrenic polymer constitutes a dispersed phasein the resin as described in copending U.S. Patent Publication No.2006-0276558, the relevant portions of which are herein incorporated byreference.

In some embodiments of the invention, the expandable polymer matrix caninclude mixtures and combinations of the above-described thermoplasticresins. In other embodiments, the above-described thermoplastic resinsor combinations of thermoplastic resins can be used in mixtures andcombinations with other polymers. The mixtures and combinations can beused to provide particular properties to the expandable polymer matrixand/or foam core, such as water impermeability, flexural strength,elastic modulus, toughness, and/or tear strength.

In particular embodiments of the invention, the expandable polymermatrix can contain 100% interpolymers of a polyolefin and in situpolymerized vinyl aromatic monomers, but can also contain up to 99%, insome cases up to 95%, in other cases up to 90%, in some instances up to80% and in other instances up to 75% based on the weight of theexpandable polymer matrix of interpolymers of a polyolefin and in situpolymerized vinyl aromatic monomers. Also, the expandable polymer matrixcan contain at least 25%, in some cases at least 30%, in other cases atleast 40% and in some instances at least 50% based on the weight of theexpandable polymer matrix of interpolymers of a polyolefin and in situpolymerized vinyl aromatic monomers. The amount of interpolymers of apolyolefin and in situ polymerized vinyl aromatic monomers in theexpandable polymer matrix can be any value or range between any of thevalues recited above.

When other expandable polymers are included in the expandable polymermatrix with the interpolymers, the other expandable polymers can bepresent at a level of at least 1%, in some cases at least 5%, in othercases at least 10%, in some instances at least 20% and in otherinstances at least 25% based on the weight of the expandable polymermatrix. Also, the other expandable polymers can be present in theexpandable polymer matrix at a level of up to 75%, in some cases up to70%, in other cases up to 60% and in some instances up to 50% based onthe weight of the expandable polymer matrix. The other expandablepolymers can be included in the expandable polymer matrix at any levelor range between any of the values recited above.

In other particular embodiments of the invention, the expandable polymermatrix can contain 100% polystyrene modified rubber, but can alsocontain up to 99%, in some cases up to 95%, in other cases up to 90%, insome instances up to 80% and in other instances up to 75% based on theweight of the expandable polymer matrix of polystyrene modified rubber.Also, the expandable polymer matrix can contain at least 25%, in somecases at least 30%, in other cases at least 40% and in some instances atleast 50% based on the weight of the expandable polymer matrix ofpolystyrene modified rubber. The amount of polystyrene modified rubberin the expandable polymer matrix can be any value or range between anyof the values recited above.

When other expandable polymers are included in the expandable polymermatrix with the polystyrene modified rubber, the other expandablepolymers can be present at a level of at least 1%, in some cases atleast 5%, in other cases at least 10%, in some instances at least 20%and in other instances at least 25% based on the weight of theexpandable polymer matrix. Also, the other expandable polymers can bepresent in the expandable polymer matrix at a level of up to 75%, insome cases up to 70%, in other cases up to 60% and in some instances upto 50% based on the weight of the expandable polymer matrix. The otherexpandable polymers can be included in the expandable polymer matrix atany level or range between any of the values recited above.

In the present invention, the thermoplastic resins can be particlespolymerized in a suspension process, which are essentially sphericalresin beads useful for making expandable thermoplastic particles.However, polymers derived from solution and bulk polymerizationtechniques that are extruded and cut into particle sized resin beadsections can also be used.

In an embodiment of the invention, thermoplastic resin beads(unexpanded) containing any of resins, polymers and/or polymercompositions described herein can have a particle size of at least 0.2,in some situations at least 0.33, in some cases at least 0.35, in othercases at least 0.4, in some instances at least 0.45 and in otherinstances at least 0.5 mm. Also, the resin beads can have a particlesize of up to 3, in some instances up to 2, in other instances up to2.5, in some cases up to 2.25, in other cases up to 2, in somesituations up to 1.5 and in other situations up to 1 mm. The resin beadsused in this embodiment can be any value or can range between any of thevalues recited above.

The expanded impregnated thermoplastic resin beads can be expandedplastics, prepuff, and/or expanded resin beads as used in the presentinvention.

The expandable thermoplastic particles or resin beads can optionally beimpregnated using any conventional method with a suitable blowing agent.As a non-limiting example, the impregnation can be achieved by addingthe blowing agent to the aqueous suspension during the polymerization ofthe polymer, or alternatively by re-suspending the polymer particles inan aqueous medium and then incorporating the blowing agent as taught inU.S. Pat. No. 2,983,692. Any gaseous material or material which willproduce gases on heating can be used as the blowing agent. Conventionalblowing agents include aliphatic hydrocarbons containing 4 to 6 carbonatoms in the molecule, such as butanes, pentanes, hexanes, and thehalogenated hydrocarbons, e.g., CFC's and HCFC's, which boil at atemperature below the softening point of the polymer chosen. Mixtures ofthese aliphatic hydrocarbon blowing agents can also be used.

Alternatively, water can be blended with these aliphatic hydrocarbonsblowing agents or water can be used as the sole blowing agent as taughtin U.S. Pat. Nos. 6,127,439; 6,160,027; and 6,242,540 in these patents,water-retaining agents are used. The weight percentage of water for useas the blowing agent can range from 1 to 20%. The texts of U.S. Pat.Nos. 6,127,439, 6,160,027 and 6,242,540 are incorporated herein byreference.

The impregnated thermoplastic resin beads are optionally expanded to abulk density of at least 0.5 lb/ft³ (0.008 g/cc), in some cases, atleast 1.25 lb/ft³ (0.02 g/cc), in other cases at least 1.5 lb/ft³ (0.024g/cc), in some situations, at least 1.75 lb/ft³ (0.028 g/cc), in somecircumstances, at least 2 lb/ft³ (0.032 g/cc) in other circumstances atleast 3 lb/ft³ (0.048 g/cc), and in particular circumstances at least3.25 lb/ft³ (0.052 g/cc) or 3.5 lb/ft³ (0.056 g/cc) thus formingpre-expanded thermoplastic beads or particles. When non-expanded resinbeads are used, higher bulk density beads can be used. As such, the bulkdensity can be as high as 40 lb/ft³ (0.64 g/cc) and when only slightlyexpanded up to 30 lb/ft³ (0.48 g/cc), in some cases up to 20 lb/ft³(0.32 g/cc), in other cases, up to 10 lb/ft³ (0.16 g/cc) and in someinstances up to 7.5 lb/ft³ (0.12 g/cc). The bulk density of thethermoplastic particles can be any value or range between any of thevalues recited above.

The expansion step is conventionally carried out by heating theimpregnated beads via any conventional heating medium, such as steam,hot air, hot water, or radiant heat. One generally accepted method foraccomplishing the pre-expansion of impregnated thermoplastic particlesis taught in U.S. Pat. No. 3,023,175.

The impregnated resin beads can be foamed cellular polymer particles astaught in U.S. Patent Publication No. 2002-0117769, the teachings ofwhich are incorporated herein by reference. The foamed cellularparticles can be any of the resins and/or polymers described above thatcan be expanded and contain a volatile blowing agent at a level of lessthan 14 wt %, in some situations less than 6 wt. %, in some casesranging from about 2 wt. % to about 5 wt. %, and in other cases rangingfrom about 2.5 wt. % to about 3.5 wt. % based on the weight of thepolymer.

When interpolymer resins are included in the expandable polymer matrix,the amount of polyolefin in the interpolymer resin of the invention canbe at least 20%, in some cases at least 25%, and in other cases at least30% and can be up to 80%, in some cases up to 70%, in other cases up to60% and in some instances up to 55%, by weight based on the weight ofthe interpolymer resin particles. The amount of polyolefin in theinterpolymer resin can be any value or range between any of the valuesrecited above.

The amount of polymerized vinyl aromatic resin in the interpolymer resinof the invention can be at least 20%, in some cases at least 30%, inother cases at least 40% and in some instances at least 45% and can beup to 80%, in some cases up to 75% and in other cases up to 70%, byweight based on the weight of the interpolymer resin particles. Theamount of polymerized vinyl aromatic resin in the interpolymer resin canbe any value or range between any of the values recited above.

The vinyl aromatic resin in the interpolymer resin can be made up ofpolymerized vinyl aromatic monomers or the resin can be a copolymercontaining monomeric units from vinyl aromatic monomers andcopolymerizable comonomers. Non-limiting examples of vinyl aromaticmonomers that can be used in the invention include styrene,alpha-methylstyrene, ethylstyrene, chlorostyrene, bromostyrene,vinyltoluene, vinylbenzene, and isopropylxylene. These monomers may beused either alone or in admixture.

Non-limiting examples of copolymerizable comonomers include1,3-butadiene, C₁-C₃₂ linear, cyclic or branched alkyl (meth)acrylates(specific non-limiting examples include butyl (meth)acrylate, ethyl(meth)acrylate and 2-ethylhexyl (meth)acrylate), acrylonitrile, vinylacetate, alpha-methylethylene, divinyl benzene, maleic anhydride,itaconic anhydride, dimethyl maleate and diethyl maleate.

Non-limiting examples of vinyl aromatic copolymers that can be used inthe interpolymer resin of invention include those disclosed in U.S. Pat.No. 4,049,594. Specific non-limiting examples of suitable vinyl aromaticcopolymers include copolymers containing repeat units from polymerizingstyrene and repeat units from polymerizing one or monomers selected from1,3-butadiene, C₁-C₃₂ linear, cyclic or branched alkyl (meth)acrylates(specific non-limiting examples including butyl (meth)acrylate, ethyl(meth)acrylate and 2-ethylhexyl (meth)acrylate), acrylonitrile, vinylacetate, alpha-methylethylene, divinyl benzene, maleic anhydride,itaconic anhydride, dimethyl maleate and diethyl maleate.

In particular embodiments of the invention, the vinyl aromatic resin inthe interpolymer resin includes polystyrene or styrene-butyl acrylatecopolymers.

In embodiments of the invention, the interpolymer resin particles areformed as follows: The polyolefin particles are dispersed in an aqueousmedium prepared by adding 0.01 to 5%, in some cases 2 to 3%, by weightbased on the weight of the water of a suspending agent such as watersoluble high molecular weight materials, e.g., polyvinyl alcohol ormethyl cellulose or slightly water soluble inorganic materials, e.g.,calcium phosphate or magnesium pyrophosphate and soap, such as sodiumdodecyl benzene sulfonate, and the vinyl aromatic monomers are added tothe suspension and polymerized inside the polyolefin particles.

Any conventionally known and commonly used suspending agents forpolymerization of vinyl aromatic monomers can be employed. These agentsare well known in the art and can be freely selected by one skilled inthe art. Initially, the water is in an amount generally from 0.7 to 5,preferably 3 to 5 times that of the starting polyolefin particlesemployed in the aqueous suspension, on a weight basis, and gradually theratio of the polymer particles to the water may reach around 1:1.

The polymerization of the vinyl aromatic monomers, which are absorbed inthe polyolefin particles, is carried out using initiators.

The initiators suitable for suspension polymerization of the vinylaromatic monomers are generally used in an amount of about 0.05 to 2percent by weight, in some cases 0.1 to 1 percent by weight, based onthe weight of the vinyl aromatic monomer. Non-limiting examples ofsuitable initiators include organic peroxides such as benzoyl peroxide,lauroyl peroxide, t-butyl perbenzoate and t-butyl perpivalate and azocompounds such as azobiisobutylonitrile and azobidimethylvaleronitrile.

These initiators can be used alone or two or more initiators can be usedin combination. In many cases, the initiators are dissolved in the vinylaromatic monomers, which are to be absorbed in the polyolefin particles.In other cases, the initiator can be dissolved in a solvent, such astoluene, benzene, and 1,2-dichloropropane.

When the in situ polymerization of the vinyl aromatic monomers iscompleted, the polymerized vinyl aromatic resin is uniformly dispersedinside the polyolefin particles.

In many cases, the polyolefin particles are cross-linked. Thecross-linking can be accomplished simultaneously with the polymerizationof the vinyl aromatic monomer in the polyolefin particles, and beforeimpregnation of the blowing agent and/or plasticizer. For this purpose,cross-linking agents are used. Such cross-linking agents include, butare not limited to di-t-butyl-peroxide, t-butyl-cumylperoxide,dicumyl-peroxide, α,α-bis-(t-butylperoxy)-p-diisopropylbenzene,2,5-dimethyl-2,5-di-(t-butylperoxy)-hexyne-3,2,5-dimethyl-2,5-di-(benzoylperoxy)-hexaneand t-butyl-peroxyisopropyl-carbonate. These cross-linking agents areabsorbed in the polyolefin particles together with the vinyl aromaticmonomers by dissolving the cross-linking agent in an amount of about 0.1to 2 weight % and in some cases 0.5 to 1 weight %, based on the weightof the polyolefin particles suspended in water. Further details of thecross-linking agents and the manner for absorbing the cross-linkingagents into the polyolefin particles are provided in U.S. Pat. No.3,959,189.

The interpolymer particles are acidified, dewatered, screened, andsubsequently charged to a second reactor where the particles areimpregnated with the blowing agent and/or plasticizer.

The impregnation step can be carried out by suspending the interpolymerparticles in an aqueous medium, adding the blowing agent and/orplasticizer to the resulting suspension, and stirring at a temperatureof, preferably, about 40° C. degrees to 80° C. The blowing agent and/orplasticizer can be blended together and then added to the interpolymerparticles or can be added to the interpolymer particles separately.

Alternatively, the blowing agent and/or plasticizer can be added to thefirst reactor during or after the polymerization process.

The above processes describe a wet process for impregnation of theinterpolymer particles. Alternatively, the interpolymer particles can beimpregnated via an anhydrous process similar to that taught in Column 4,lines 20-36 of U.S. Pat. No. 4,429,059.

When polystyrene modified rubber resins are included in the expandablepolymer matrix, these resins can be made by forming a dispersion oforganic droplets by pressure atomizing an organic liquid mixture belowthe free surface of an aqueous phase, which can be stationary orflowing, or by applying mechanical agitation. The organic mixturetypically contains an organic solution that includes one or moreelastomeric polymers and/or one or more polyolefins dissolved in amonomer solution containing one or more styrenic monomers. The dispersedorganic droplets typically have an average diameter of from about 0.001mm to about 10 mm. The monomers are typically polymerized, usinginitiators as described above, in the dispersed organic droplets in alow shear flow pattern to form unexpanded polymer beads. In many cases,the organic mixture has a density of ±20% of the density of the aqueousphase and the dispersed organic droplets make up from 0.01 to 60 volumepercent of the total volume of the organic and aqueous liquids.

In some embodiments, the low shear flow pattern is a controlled lowturbulence flow pattern created, without mechanical agitation, bycontinuously or periodically injecting at gauge pressure up to 15 barinto selected parts of the reactor one or more streams of a gas inert tothe reactor contents and immiscible with the reactor contents. The gascan be injected into the aqueous phase at a gauge pressure less than 3bar and can form one or more streams of bubbles having diameterssubstantially larger than the average size of the atomized organicdroplets.

In some embodiments, the low shear flow pattern is provided bymechanical agitation.

Typically, the unexpanded polystyrene modified rubber resin beads have acontinuous phase and a dispersed phase and the continuous phase includesthe elastomeric polymers and/or polyolefins in a crosslinked webmorphology. The continuous phase can also include elastomeric polymersand/or polyolefins in a morphology that includes threads having a largeaspect ratio, which are optionally at least partially crosslinked and/orconnected via locally formed branches and/or an interconnected meshstructure.

In many embodiments, the organic mixture contains from about 5 to about50 wt. %, based on the weight of the organic mixture, of one or moreelastomeric polymers and/or one or more polyolefins and from about 95 toabout 50 wt. % of a monomer solution that includes one or more styrenicmonomers, where the elastomeric polymers and/or one or more polyolefinsare soluble in the monomer solution.

In embodiments of the invention, the elastomeric polymers can beselected from homopolymers of butadiene or isoprene, and random, block,AB diblock, or ABA triblock copolymers of a conjugated diene with anaryl monomer and/or (meth)acrylonitrile and random, alternating or blockcopolymers of ethylene and vinyl acetate.

In some embodiments of the invention, the elastomeric polymers includeone or more block copolymers selected from diblock and triblockcopolymers of styrene-butadiene, styrene-butadiene-styrene,styrene-isoprene, styrene-isoprene-styrene, ethylene-vinyl acetate,partially hydrogenated styrene-isoprene-styrene and combinationsthereof. In other embodiments of the invention, the elastomeric polymersinclude one or more copolymers containing repeat units from thepolymerization of one or more conjugated diene and at least oneunsaturated nitrile selected from acrylonitrile and methacrylonitrile.

In an embodiment of the invention, the blowing agent can be dosed to theexpandable polymer matrix in an extruder to produce resin pellets orbeads. The extruder acts to mix the blowing agent into the expandablepolymer matrix prior to extruding a strand of the mixture. The strandcan be cut into bead or pellet lengths using an appropriate device, anon-limiting example being an underwater face cutter.

The particles and/or beads of the expandable polymer matrix according tothe invention can also contain other additives known in the art,non-limiting examples including nucleating agents, anti-staticadditives; flame retardants; colorants or dyes; filler materials andcombinations thereof. Other additives can also include chain transferagents, non-limiting examples including C₂₋₁₅ alkyl mercaptans, such asn-dodecyl mercaptan, t-dodecyl mercaptan, t-butyl mercaptan and n-butylmercaptan, and other agents such as pentaphenyl ethane and the dimer ofalpha-methyl styrene. Other additives can further include nucleatingagents, non-limiting examples including polyolefin waxes, i.e.,polyethylene waxes.

The resulting expandable polymer matrix is used as a raw material inproducing foam cores and/or blanks in the present sports boards. Theblowing agent and/or plasticizers are introduced into the expandablepolymer matrix resin particles to form foamable or expandable particlesor resin beads, which in turn, are used to mold foam cores.

The blowing agent should have a boiling point lower than the softeningpoint of the polyolefin and should be gaseous or liquid at roomtemperature (about 20 to 30° C.) and normal pressure (aboutatmospheric). Blowing agents are well known in the art and generallyhave boiling points ranging from −42° C. to 80° C., more generally, from−10° C. to 36° C. Suitable hydrocarbon blowing agents include, but arenot limited to aliphatic hydrocarbons such as n-propane, n-butane,iso-butane, n-pentane, iso-pentane, n-hexane, and neopentane,cycloaliphatic hydrocarbons such as cyclobutane and cyclopentane, andhalogenated hydrocarbons such as methyl chloride, ethyl chloride,methylene chloride, trichlorofluoromethane, dichlorofluoromethane,dichlorodifluormethane, chlorodifluoromethane anddichlorotetrafluoroethane, etc. These blowing agents can be used aloneor as mixtures. If n-butane, ethyl chloride, anddichlorotetrafluoroethane, which are gaseous at room temperature andnormal pressure, are used as a mixture, it is possible to achievefoaming to a low bulk density. Specific types of volatile blowing agentsare taught in U.S. Pat. No. 3,959,180. In particular embodiments of theinvention, the blowing agent is selected from n-pentane, iso-pentane,neopentane, cylcopentane, and mixtures thereof.

The amount of the blowing agent ranges from about 1.5% to about 20% byweight, in some cases, about 1.5% to 15% by weight, and, in other cases,from 5% to 15% by weight, based on the weight of the expandable polymermatrix.

A plasticizer can be used in combination with the blowing agent and asstated herein above and acts as a blowing aid in the invention.

Suitable plasticizers include, but are not limited to benzene, toluene,limonene, linear, branched or cyclic C₅ to C₂₀ alkanes, white oil,linear, branched or cyclic C₁ to C₂₀ dialkylphthalates, styrene,oligomers of styrene, oligomers of (meth)acrylates having a glasstransition temperature less than polystyrene, and combinations thereof.

In a particular embodiment of the invention, the plasticizer includeslimonene, a mono-terpene hydrocarbon existing widely in the plant world.The known types are d-limonene, 1-limonene, and dl-limonene. D-limoneneis contained in the skin of citrus fruits and is used in food additivesas a fragrant agent; its boiling point is about 176° C.; and itsflammability is low. D-limonene is a colorless liquid, has a pleasantorange-like aroma, is approved as a food additive, and is widely used asa raw material of perfume. Limonene is not a hazardous air pollutant.

The amount of plasticizer can range from about 0.1 to 5 parts and insome cases from about 0.1 to about 1 part, by weight per 100 parts byweight of the expandable polymer matrix.

In many embodiments of the invention, the pre-expanded beads orparticles containing the expandable polymer matrix are molded into afoam core shape of desired dimensions by adding pre-expanded particlesor beads after four to 48 hours of ageing to completely fill a mold ofthe desired shape and dimensions and molding in a steam molding press.When steam is applied uniformly to the pre-expanded particles or beads,good fusion between beads is accomplished. When heat is also appliedfrom the mold and/or mold press, a skin can be formed on the outersurface of the molded foam core.

The skin that is formed during molding provides a surface that readilyaccepts paint as well as laminating resins.

In prior art methods, the pre-expanded beads or particles are moldedinto a generally rectangular shape mold. The foam core is then preparedby cutting the general foam core shape into the block molded foam andthen shaping the desired curvature to provide the foam core. This methodis typically used in the prior art and results in any skin of the moldedpart being removed and the fused cell structure of the foam core beingseverely disrupted. This method results in significantly higher waterabsorption in the foam core as well as incompatibility with paint andlaminating resins. The latter typically results in a non-uniform or wavysurface in the sports board, which is aesthetically undesirable andmakes the sports board less aerodynamic.

In embodiments of the invention, these problems have been overcome bydirectly molding the foam core into its desired shape as described aboveto form a skin and/or by applying a sealant to the damaged surfacecreated by cutting in the foam core shape.

Any sealant coating can be used that provides water repellant propertiesto the surface of the foam core and provides a surface that acceptslaminating resins with little to no wrinkling or other surfacedeformation. Suitable sealants are formulations that include, but arenot limited to, ethylene-vinyl acetate copolymers, ethylene-vinylalcohol copolymers, ethylene-acrylic acid copolymers, styrene-butadienepolymers, styrene-isoprene polymers; styrene-butadiene-styrene blockpolymers; styrene-isoprene-styrene block polymers; and hydrogenatedresins thereof and combinations thereof.

Other materials that can be used as or as part of the sealant, in someinstances, include joint compound, gypsum paste, polyurethanes, styrenicblock copolymers, polypropylene, and polyethylene.

In some embodiments, the sealant can be multilayered, including layersthat contain any of the materials indicated above. Having one or morelayers and the composition of those layers is determined based on thecomposition of the foam core and the composition of the upper layercovering and under layer covering. As a non-limiting example, sealantcan include three components, a thermoplastic polyolefin; athermoplastic styrenic polymer; and a styrenic block copolymer.

In some instances, the sealant includes film structures containing from35 to 65 weight % of thermoplastic olefin, in some cases, from 55 to 60weight %; from 10 to 30 weight % thermoplastic styrenic polymer, in somecases, from 15 to 20 weight %, with the balance being a styrenic blockcopolymer.

In particular instances, the sealant can include from 20 to 60 weight %polypropylene, in some cases, 40 to 50 weight %; from 20 to 60 weight %polystyrene, in some cases, from 40 to 50 weight %, with the balancebeing a styrenic block copolymer.

The styrenic block copolymer used in the sealant can be a copolymer ofat least one vinyl aromatic monomer and at least one other olefin,diolefin and/or diene monomer. In particular embodiments, the styreneblock copolymers can contain blocks of styrene and blocks of butadienewith from about 35 to 55 weight % bound styrene and a number averagemolecular weight (determined using gel permeation chromatography withpolystyrene standards) of from about 50,000 to about 100,000.Non-limiting example of suitable styrenic block copolymers are thoseavailable under the trademark KRATON® from KRATON Polymers U.S. L.L.C.of Houston, Tex.

In some embodiments, the sealant includes multilayer structures thatcontain at least three layers, a thermoplastic polyolefin layer (TPO); athermoplastic vinyl aromatic layer (TVA); and a tie layer (TL) which islocated between the TLO layer and the TVA layer. This can be describedas a TPO/TL/TVA structure. In some specific embodiments, the sealant caninclude film structures containing five layers, with the TVA layer beingthe core layer, as a non-limiting example, a five layer structure can bedescribed as TPO/TL/TVA/TL/TPO.

When the sealant includes multilayer films, in many cases, the sealantcontains about 5 to 25 weight % of tie layer material (based on thetotal weight of the multilayer structure). The tie layers can be used inamounts of from 5 to 10 weight % when preparing sheet structures, thoughit is possible to prepare useful structures, which contain less than 1%tie layer material. The amount of material used in the other layers canbe widely varied to suit different end use. As a non-limiting example, amultilayer film containing similar amounts of polyolefin andthermoplastic styrenic polymer (e.g., from 10 to 20 weight % “tie layer”and 40-50 weight % in each of the TPO and TVA layers.

It is also within the scope of the invention to pre-mix the tie layermaterial with a part of the material used for one of the outer layers.This method can be used when only a very small weight % of the overallstructure is contained in either the TPO layer of the TVA layer.

In embodiments of the invention, the foam cores described herein have ameasured water absorption (measured according to ASTM C-272) of lessthan 2, in some cases, less than 1, and, in other cases, less than 0.5volume percent determined on a sample molded to a density of from 1.5 to2.5 lb/ft³ (0.024 to 0.04 g/cc).

In other embodiments of the invention, the foam cores described hereinare made from materials that have a flexural strength at 5% strain(measured according to ASTM C-203) of at least 20 psi, in some cases, atleast 25 psi and, in other cases, at least 30 psi at a molded density ofabout 1.5 lb/ft3 (0.024 g/cc); at least 30 psi, in some cases, at least35 psi and, in other cases, at least 40 psi at a molded density of about1.75 lb/ft3 (0.028 g/cc); at least 40 psi, in some cases, at least 45psi and, in other cases, at least 50 psi at a molded density of about 2lb/ft3 (0.032 g/cc); and at least 60 psi, in some cases, at least 65 psiand, in other cases, at least 70 psi at a molded density of about 2.25lb/ft3 (0.036 g/cc).

In additional embodiments of the invention, the foam cores describedherein are made from materials that have a tensile strength (measuredaccording to ASTM D-3575-T) of at least 25 psi, in some cases, at least30 psi and, in other cases, at least 35 psi at a molded density of about1.5 lb/ft³ (0.024 g/cc); at least 40 psi, in some cases, at least 45 psiand, in other cases, at least 50 psi at a molded density of about 1.75lb/ft³ (0.028 g/cc); at least 55 psi, in some cases, at least 60 psiand, in other cases, at least 65 psi at a molded density of about 2lb/ft³ (0.032 g/cc); and at least 75 psi, in some cases, at least 80 psiand, in other cases, at least 85 psi at a molded density of about 2.25lb/ft³ (0.036 g/cc).

In additional embodiments of the invention, the foam cores describedherein are made from materials that have a foam tear strength (measuredaccording to ASTM D-3575-G) of at least 5 lb/in, in some cases, at least5.5 lb/in and, in other cases, at least 6 lb/in at a molded density ofabout 1.2 lb/ft³ (0.019 g/cc); at least 9 lb/in, in some cases, at least10 lb/in and, in other cases, at least 11 lb/in at a molded density ofabout 1.5 lb/ft³ (0.024 g/cc); at least 12 lb/in, in some cases, atleast 13 lb/in and, in other cases, at least 14 lb/in at a moldeddensity of about 1.75 lb/ft³ (0.028 g/cc); at least 15 lb/in, in somecases, at least 17 lb/in and, in other cases, at least 18 lb/in at amolded density of about 2 lb/ft³ (0.032 g/cc); and at least 19 lb/in, insome cases, at least 20 lb/in and, in other cases, at least 22 lb/in ata molded density of about 2.25 lb/ft³ (0.036 g/cc).

Advantageously, the foam cores described herein have improved waterrepellant properties compared to expanded polystyrene foam cores in theprior art in that they absorb much less moisture and, therefore, do nottake on undesirable weight when exposed to water.

Additionally, the foam cores described herein have higher tensilestrength compared to expanded polyethylene or expanded polypropylenefoam cores of the same density so the present foam cores are less likelyto break during use.

Once the foam core has been made, an upper layer covering at least aportion of the upper surface of the foam core and an under layercovering at least a portion of the under surface of the foam core areapplied.

In embodiments of the invention, upper layer covering and under layercovering include fibrous mats or fibrous fabric. The mats or fabric canbe conventional and contain fibers such as glass fibers, aramide fibers,polyamide fibers, carbon fibers, silicon carbide fibers, compositefibers, metal fibers, fiberglass, and combinations thereof as well asfabric containing the above-mentioned fibers, and fabric containingcombinations of the above-mentioned fibers.

When the prefabricated foam core has had one or more fibrous layersapplied as the upper layer covering and/or under layer covering, alaminating resin is poured onto the fibrous mats at the upper and/orunder surfaces of the foam core. The laminating resin can then beallowed to cure and harden, securing the fibrous layer(s) of the upperlayer covering and/or under layer covering to the foam core.

In embodiments of the invention, after the laminating resin has beenapplied, the thus treated foam core or blank is inserted in a lower moldsegment of a mold press in which the fibrous layer(s) with laminatingresin is held by vacuum, and the mold press is closed. The pressure ofthe press causes the laminating resin to be completely distributed inthe space between the foam core and the fibrous layer(s) and cures toform a closed fiber-reinforced shell, which comes into intimateconnection with the foam core. The curing step can take place at amolding tool temperature of at least about 80° C. and for at least about5 minutes.

After curing, the projecting film edges of the laminated foam core canbe trimmed. Thereafter, the cut faces can optionally be sealed.

The laminating resin used to saturate the fibrous layer(s) is typicallya resin system-catalyst component system that includes a resin system, acure catalyst, and optionally filler materials.

In embodiments of the invention, the laminating resin can be apolyurethane formulation that includes a polyalcohol component and anisocyanate component; an epoxy formulation that includes an epoxycontaining component and a reactive component such as a polyalcoholcomponent; a curable polyester formulation that includes an unsaturatedpolyester resin component and a peroxide component, non-limitingexamples of suitable peroxides include methyl ethyl ketone peroxide,hydrogen peroxide, benzoyl peroxide, lauroyl peroxide, t-butylperbenzoate, t-butyl perpivalate di-t-butyl-peroxide,t-butyl-cumylperoxide, dicumyl-peroxide,α,α-bis-(t-butylperoxy)-p-diisopropylbenzene,2,5-dimethyl-2,5-di-(t-butylperoxy)-hexane-3,2,5-dimethyl-2,5-di-(benzoylperoxy)-hexaneand t-butyl-peroxyisopropyl-carbonate; a mixture of dimethyl phthalateand an ester plasticizer and methyl ethyl ketone peroxide secondcomponent; acrylic unsaturated polyester resins as disclosed in U.S.Pat. No. 5,395,866; epoxide-vinyl ester resins as disclosed in U.S. Pat.No. 4,595,734; and combinations thereof. The relevant portions of U.S.Pat. Nos. 5,395,866 and 4,595,734 are herein incorporated by reference.

In embodiments of the invention, the laminating resin system includes acurable unsaturated polyester resin and optionally a co-curableunsaturated monomer.

Curable unsaturated polyester resins are known in the art, and aregenerally prepared in a non-limiting sense, by esterification ortransesterification of one or more unsaturated dicarboxylic acids orreactive derivatives thereof with one or more aliphatic orcycloaliphatic diols. Saturated dicarboxylic acids, aromaticdicarboxylic acids, or their reactive derivatives can be used inconjunction with the unsaturated dicarboxylic acid(s) to lower thecrosslink density. Curable polyester resins are available commercially,and examples of such are disclosed in, as non-limiting examples, U.S.Pat. Nos. 3,969,560; 4,172,059; 4,491,642; 4,626,570, and 6,226,958which are herein incorporated by reference.

The curable unsaturated polyester resins can be a high reactivitypolyester resin. Non-limiting examples of suitable high reactivitypolyester resins include, but are not limited to, high reactivityorthophthalic polyester resins, high reactivity isophthalic polyesterresins, and high reactivity dicyclopentadiene-modified (DCPD) polyesterresins. A particular non-limiting example of a curable unsaturated highreactivity polyester resin is a dicyclopentadiene-modified propyleneglycol-maleate polyester resin.

Co-curable unsaturated monomers are also well known in the art, andinclude, as non-limiting examples, the various alkylacrylates andalkylmethacrylates as well as vinyltoluene .alpha.-methylstyrene,p-methylstyrene, and styrene. By the term “co-curing,” it is meant thatthe monomer contains reactive unsaturation capable of reacting withitself and/or the unsaturated sites of the curable polyesters under thecuring conditions. Additional co-curable monomers are identified in theabove-referenced patents. A non-limiting example of a co-curable monomeris styrene.

Non-limiting examples of suitable laminating resins include the SILMAR®and CoREZYN® products available from Interplastic Corporation, SaintPaul, Minn., the HI-POINT resins available from Crompton Corporation,Middlebury, Conn. and the polyester resins, a non-limiting example beingPolyester Resin 30P-105, available from Dura Technologies, Inc.,Bloomington, Calif.

Suitable fibrous layer fabric that can be used in the inventionincludes, but is not limited to, the above-described fibers in thefollowing forms: plain weave, 14 mils thick cloth; plain weave, 11 milsthick cloth; plain weave, 10 mils thick cloth; plain weave, 8 mils thickcloth; plain weave, 5.5 mils thick cloth; four harness satin weave, 3.5mils thick cloth; 2/2 twill weave, 9.3 mils thick cloth; modified plainweave, 7.7 mils thick cloth; eight harness satin weave, 8 mils thickcloth; eight harness satin weave, 9 mils thick cloth; and layers ofcombinations of such fabrics.

The sports boards utilizing the foam cores or blanks and methods ofconstruction according to the invention provide boards that have a rapid“flex memory”, the ability of a board to very quickly “spring” back toits original shape when deformed. Flex memory can provide, for example,improved acceleration when surfing and improved turning radius andacceleration when snowboarding. Thus, flex memory is a desirableattribute that has proved elusive in prior art sports boards.

Sports boards constructed according to the invention can be evaluatedusing an Emerson 8510 compression tester, (Emerson Apparatus Company,Inc., Portland, Me.), designed in accordance with the requirements ofASTM D642 and TAPPI T804 equipment specifications. In these evaluations,a programmable platen is set at a rate of 0.5 inches (1.27 cm) perminute using a fixture of the type used in test protocols for alpineskis, a three point bending test as described in ASTM Standard 780-93a.

In this evaluation, the sports board is supported near each end by a1.5″ diameter free floating steel rod so as to not apply any friction tothe base of the board as it is being deflected from the top using alaminated structure that includes a rubber compliant fixture (19 incheslong×1.5 inches wide) that follows the contour of the sports board deckso as to apply an equal amount of force across its width.

The amount of deflection that the sports boards according to theinvention can withstand without breaking is greater than what isobserved when compared to prior art sports boards.

Additionally, where prior art sports boards fail catastrophically are nolonger capable of supporting a load, the sports boards constructedaccording the invention are able to continue to support a load evenafter failure. In other words, where prior art sports boards break,sports boards constructed according the invention bend and are toughenough to maintain some structural integrity.

An embodiment of the sports boards according to the invention is asurfboard as shown in FIGS. 1-4. Surfboard 10 has foam core elements 12and 14 as described above separated by stringer 16 where foam coreelements 12 and 14 are located on each side of stringer 16. Stringer 16can be made of wood, carbon/graphite reinforced material, compositematerial, metal and/or combinations of such materials.

During manufacture, stringer 16 can be bowed in a gentle curve downwardfor its entire length to form a rocker shape from nose 18 to tail 20.Stringer 16 can be first formed with an upward curve from theapproximate center to ends and relatively thicker structure in nose 18half of stringer 16 relative to tail 20. Tail 20 half of stringer 16 isapproximately straight at this step of the manufacture. Stringer 16 canthen be further bowed downward under pressure in a stringer bending formto produce a gentle curve downward for approximately one half of itslength from tail 20 to complete the overall rocker shape. Tail 20 endbeing relatively thinner bends in the bending form as compared to nose18 end.

Thus a tail 20 with a top 22 concave and bottom 23 convex curved shapelongitudinally is created. In addition, stringer 16 is thereby in astress or spring condition with energy and tends to return to theoriginal straight shape. Therefore, any force tending to bend tail 20end upward must act against this spring force, thus providing a strongresistance to bending in an upward direction and a strong force toreturn to the original shape. Unique in the present invention is theadded spring force supplied by the foam core acting to restore thesurfboard to its original shape.

Upper layer covering 24 and under layer covering 26, as described morefully above are bonded to cover foam core elements 12 and 14 andstringer 16 to form outer layer 28 of surfboard 10. Outer layer 28includes two components, a laminating resin with optionally addedfillers and a fabric as described above.

Wood framed, metal or fiber reinforced epoxy framed fins 30 can beattached on bottom 23 near the tail 20.

The use of the present foam core elements 12 and 14 provides a flexiblereinforced construction relative to nose 18 and tail 20 in that portionof surfboard 10. This, in combination with stringer 16, provides forflexure in the midsection of surfboard 10 which is torsional aboutstringer 16. Further, the density of foam core elements 12 and 14 can behigher at the nose 18 and tail 20 ends, and lower in the areas betweento further provide flexure in the midsection of surfboard 10. Stateddifferently, the more foam core elements 12 and 14 allow nose 18 andtail 20 portions to tend to twist about stringer 16 when under pressure,or force of bending when used in surfing, in the water while nose 18 andtail 20 portions will tend to remain rigid, the greater the resultingspring back force will be. Optionally, in order to construct differencesin flexure in surfboard 10, upper layer covering 24 and under layercovering 26 can be varied in stiffness by varying their respectivethickness and/or composition. As a non-limiting example, nose 18 areacan be relatively rigid, tail 20 area can be relatively rigid and thearea in between can be relatively flexible.

This design provides for additional surfing or planning speed due to thespring and torsional action or rapid flex memory of tail 20 in thewater. This feature provides for stability and ease of turning due tothe relative flexibility and shape between the flexible area and therelatively rigid nose 18 and tail 20 ends of surfboard 10.

The embodiments shown in FIG. 4 utilize foam core elements 12 and 14molded directly into their final shape, or molded nearly into the finalshape and cut in half. As described above, directly molding the foamcore to its final shape allows for a skin to form on the core elementsthat is not damaged by the laminating resin. FIG. 5 shows an embodimentof the invention where the foam core elements have been molded and thencut to their final shape. In this embodiment, the outer surfaces of foamcore elements 12 and 14 and optionally stringer 16 are coated withsealant coating 32 prior to upper layer covering 24 and under layercovering 26 being affixed to foam core elements 12 and 14 and stringer16.

An embodiment of the sports boards, according to the invention, is asurfboard as shown in FIGS. 6-9. Surfboard 110 has a foam core 112 asdescribed above and a parabolic stringer 116 attached to the outercircumference of foam core 112. Parabolic stringer 116 can be made ofwood, carbon/graphite reinforced material, composite material or metal.

In embodiments of the invention, parabolic stringer 116 can be made intwo elements that are constructed such that the ends of each elementaccept and/or attach to each other. As a non-limiting example, at nose118 and tail 120, the ends of each element of parabolic stringer 116 canbe attached to each other.

During manufacture, parabolic stringer 116, or its individual elements,can be bowed in a gentle curve downward for its entire length to form arocker shape from nose 118 to tail 120. Parabolic stringer 116 can befirst formed with an upward curve from the approximate center to endsand relatively thicker structure in nose 118 half of parabolic stringer116 relative to tail 120. Tail 120, half of parabolic stringer 116, orits elements is approximately straight at this step of the manufacture.Parabolic stringer 116, or its elements, can then be further boweddownward under pressure in a stringer bending form to produce a gentlecurve downward for approximately one half of its length from tail 120,to complete the overall rocker shape. Tail 120 end being relativelythinner, bends in the bending form as compared to nose 118 end.

Thus a tail 120 with a top 122 concave and bottom 123 convex curvedshape longitudinally is created. In addition, parabolic stringer 116 isthereby in a stress or spring condition with energy and tends to returnto the original straight shape. Therefore, any force tending to bendtail 120 end upward must act against this spring force, thus providing astrong resistance to bending in an upward direction and a strong forceto return to the original shape. Unique in the present invention is theadded spring force supplied by foam core 112 acting to restore thesurfboard to its original shape.

Upper layer covering 124 and under layer covering 126, as described morefully above, are bonded to cover foam 112 and parabolic stringer 116 toform outer layer 128 of surfboard 110. Outer layer 128 includes twocomponents, a laminating resin with optionally added fillers and afabric as described above.

Wood framed, metal or fiber reinforced epoxy framed fins 130 can beattached on bottom 123 near the tail 120.

In embodiments of the invention, the cross section of parabolic stringer116 or its elements can have an inner surface 114 that is concave asshown in FIG. 9 or roughly perpendicular to top 122 and bottom 123 orstraight as shown in FIG. 10.

The use of the present foam core 112 provides a flexible reinforcedconstruction relative to nose 118 and tail 120 in that portion ofsurfboard 110. This, in combination with parabolic stringer 116,provides for flexure in the midsection of surfboard 110, which istorsional about parabolic stringer 116. Further, the density of foamcore 112 can be higher at the nose 118 and tail 120 ends and lower inthe areas between, to further provide flexure in the midsection ofsurfboard 110. Stated differently the more foam core 112 allows nose 118and tail 120 portions to tend to twist in relation to parabolic stringer116, when under pressure or force of bending, when used in surfing inthe water while nose 118 and tail 120 portions will tend to remainrigid, the greater the resulting spring back force will be. Optionally,in order to construct differences in flexure in surfboard 110, upperlayer covering 124 and under layer covering 126 can be varied instiffness by varying their respective thickness and/or composition. As anon-limiting example, nose 118 area can be relatively rigid, tail 120area can be relatively rigid and the area in between can be relativelyflexible.

This design provides for additional surfing or planning speed due to thespring and torsional action or rapid flex memory of tail 120 in thewater. This feature provides for stability and ease of turning due tothe relative flexibility and shape between the flexible area and therelatively rigid nose 118 and tail 120 ends of surfboard 110. Thepresent foam core and design allow surfers using surfboards according tothe invention to traverse even the most gnarly waves.

The embodiments shown in FIG. 9 utilize foam core 112 molded directlyinto its final shape, or molded nearly into the final shape andparabolic stringer 116 either attached thereto or placed in a mold whilefoam core 112 is being molded. As described above, directly molding foamcore 112 to its final shape allows for a skin to form on the foam corethat is not damaged by the laminating resin. FIG. 10 shows an embodimentof the invention where the foam core has been molded and then cut to itsfinal shape. In this embodiment, the outer surfaces of foam core 112 andoptionally stringer 116 are coated with sealant coating 132 prior toupper layer covering 124 and under layer covering 126 being affixed tofoam core 112 and stringer 116.

In embodiments of the present invention, the above-described surfboardsinclude an elongate, water resistant or impervious, foam core containingan interpenetrating network of one or more polyolefins and one or morepolymers of vinyl aromatic monomers having an upper surface and an undersurface; an upper layer covering at least a portion of the uppersurface; and an under layer covering at least a portion of the undersurface, where the foam core is made of a foam material that has a waterabsorption (measured according to ASTM C-272) of less than 2 volumepercent at a density of from 1.5 to 2.5 lb/ft³.

The surfboards according to the invention can be provided in anysuitable length, such as big gun (9-foot or longer), longboard (8-10feet long) or short board (less than 8 feet) lengths. When surfs up, thepresent surfboards provide a rider with the ability to takeoff and shootthe curl of the most mondo, cruncher or pounder wave in a quasimoto orother position and walk the board or perform shred, ripping, cut back,cut out, pull out and/or re-entry moves with ease. Most importantly,when using the present surfboards, a dude or dudette can catch a wave,get locked in and tubed, while screaming “banzai,” “cowabunga” or otherappropriate expletives while enjoying a totally excellent gnarlatiousride.

FIG. 11 shows body board 210 configured to support a rider in water, hasa generally elongate shape defining a longitudinal axis A, a nose end212, and a tail end 214. An elongate foam core 216, as described above,provides the main bulk of body board 210, and foam core 216 issurrounded by an upper layer 218 and an under layer 220, as well as sidelayers 222 and 226 all bonded to core 216 as described above.

Upper layer 218, under layer 220 and side layers 222 and 226, asdescribed more fully above, are bonded to cover foam core 216 and toform outer layer 228 of body board 210. Outer layer 228 includes twocomponents, a laminating resin with optionally added fillers and afabric as described above.

The use of the present foam core 216 provides a flexible reinforcedconstruction relative to nose 212 and tail 214 in that portion of bodyboard 210. This in combination with upper layer 218, under layer 220 andside layers 222 and 226 provides for flexure in the midsection of bodyboard 210 which is torsional about longitudinal axis A. Further, thedensity of foam core 216 can be higher at the nose 212 and tail 214 endsand lower in the areas between to further provide flexure in themidsection of body board 210. Stated differently the more foam core 216allows nose 212 and tail 214 portions to tend to twist in relation tolongitudinal axis A, when under pressure, or force of bending when usedin riding waves in the water while nose 212 and tail 214 portions willtend to remain rigid, the greater the resulting spring back force willbe. Optionally, in order to construct differences in flexure in bodyboard 210, upper layer 218, under layer 220 and side layers 222 and 226can be varied in stiffness by varying their respective thickness and/orcomposition. As a non-limiting example, nose 212 area can be relativelyrigid, tail 214 area can be relatively rigid and side layers 222 and 226can be relatively flexible.

This design provides for additional planning speed due to the spring andtorsional action or rapid flex memory of tail 214 in the water. Thisfeature provides for stability and ease of turning. The present foamcore and design allow surfers using surfboards according to theinvention to traverse even the most gnarly waves.

The embodiments shown in FIG. 13 utilizes foam core 216 molded directlyinto its final shape, or molded nearly into the final shape. Asdescribed above, directly molding foam core 216 to its final shapeallows for a skin to form on the foam core that is not damaged by thelaminating resin. FIG. 14 shows an embodiment of the invention where thefoam core has been molded and then cut to its final shape. In thisembodiment, the outer surfaces of foam core 216 is coated with sealantcoating 230 prior to upper layer 218, under layer 220 and side layers222 and 226 being affixed to foam core 216.

Body boards according to the present invention are not distorted by flexand torsion stress and readily allow for successful completion ofmaneuvers by responding to the rider's steering. External forces do nottend to distort the present body board, making it easier for a rider toredirect the board. Thus, adequate and properly placed stiffness isprovided in the present body board. Further, sufficient flex is alsoprovided in the present body board, allowing the rider to pull up thenose, distorting it above the plane of the main deck of the body boardto keep the nose and lead corners from dropping under the water'ssurface in a dynamic situation where the nose is being forceddownwardly. Thus, flexibility for “power turns” and strength in the midand tail sections for speed can readily be provided in the present bodyboard.

FIG. 15 shows water ski 310 configured to support a rider in a standingposition while being towed by a motorized watercraft on water, has agenerally elongate shape defining a longitudinal axis A, a nose end 312,and a tail end 314. An elongate foam core 316, as described above,provides the main bulk of water ski 310, and foam core 316 is surroundedby an upper layer 318 and an under layer 320, as well as side layers 322and 326 all bonded to core 316 as described above.

Upper layer 318, under layer 320 and side layers 322 and 326, asdescribed more fully above, are bonded to cover foam core 316 and toform outer layer 328 of water ski 310. Outer layer 328 includes twocomponents, a laminating resin with optionally added fillers and afabric as described above.

Front foot insert 332 and back foot insert 334 can be attached to top321 approximately midway between nose end 312 and tail end 314, oradjusted as desired. When two water skis 310 are used by a rider, eachski has front foot insert 332 and back foot insert 334 and the skier caninsert a foot into each and ski conventionally. When slalom skiing isdesired, second foot holder 336 can be attached to top 321 between backfoot insert 334 and tail 314. Front foot insert 332, back foot insert334, and second foot holder 336 can be constructed of a generallyelastomeric material and attached to top 321 as is known in the art.

Wood framed or fiber reinforced epoxy framed fins 333 can be attached onbottom 323 near the tail 120.

The use of the present foam core 316 provides a flexible reinforcedconstruction relative to nose 312 and tail 314 in that portion of waterski 310. This in combination with upper layer 318, under layer 320 andside layers 322 and 326 provides for flexure in the midsection of waterski 310 which is torsional about longitudinal axis A. Further, thedensity of foam core 316 can be higher at the nose 312 and tail 314 endsand lower in the areas between to further provide flexure in themidsection of water ski 310. Stated differently, the more foam core 316allows nose 312 and tail 314 portions to tend to twist in relation tolongitudinal axis A when under pressure or force of bending when used inwater skiing while nose 312 and tail 314 portions will tend to remainrigid, the greater the resulting spring back force will be. Optionally,in order to construct differences in flexure in water ski 310, upperlayer 318, under layer 320 and side layers 322 and 326 can be varied instiffness by varying their respective thickness and/or composition. As anon-limiting example, nose 312 area can be relatively rigid, tail 314area can be relatively rigid and side layers 322 and 326 can berelatively flexible.

This design provides for additional planning speed due to the spring andtorsional action or rapid flex memory of tail 314 in the water. Thisfeature provides for stability and ease of turning.

The embodiments shown in FIG. 17 utilizes foam core 316 molded directlyinto its final shape, or molded nearly into the final shape. Asdescribed above, directly molding foam core 316 to its final shapeallows for a skin to form on the foam core that is not damaged by thelaminating resin. FIG. 18 shows an embodiment of the invention where thefoam core has been molded and then cut to its final shape. In thisembodiment, the outer surfaces of foam core 316 are coated with sealantcoating 330 prior to upper layer 318, under layer 320 and side layers322 and 326 being affixed to foam core 316.

FIGS. 19 and 20 show snowboard assembly 410 that includes snowboard 412to which a pair of bindings 414 are mounted to top side 416 snowboard412. Bindings 414 can be conventionally mounted to a center portionsnowboard 412.

FIG. 21 is a cross-section through snowboard 412 of FIGS. 19 and 20.Snowboard 412 includes foam core 418 completely surrounded by a skin 420that includes upper layer 422, under layer 424 and side layers 426 and428. Skin 420 as described more fully above is bonded to cover foam core418 and includes two components, a laminating resin with optionallyadded fillers and a fabric as described above.

The density of foam core 418 can vary along the length of snowboard 412.As an example, the density of foam core 412 can be lower at tip portion430 and tail portion 432 compared to mid portion 436.

The presently constructed snowboard assembly 410 has a mass moment ofinertia, also called swing weight, that is reduced while maintaining adesired shear strength and compressive strength of the snowboard. Thereduced swing weight permits snowboarders to more easily perform manymaneuvers; especially turns.

In embodiments of the invention, the shear strength and crush(compression) strength of foam core 418 between top surface 416 andbottom surface 417 is sufficiently high to provide the desired swingweight.

In embodiments of the invention, the density of foam core 418 is no morethan about 33% of the density of foam core 418 at mid portion 436.

The use of the present foam core 418 provides a flexible reinforcedconstruction relative to tip portion 430 and tail portion 432 in thatportion of snowboard 412. This, in combination with upper layer 422,under layer 424 and side layers 426 and 428 can provide for flexure inthe midsection of snowboard 412 which can be torsional aboutlongitudinal axis A. As a non-limiting example, the more foam core 418allows tip portion 430 and tail portion 432 to twist in relation tolongitudinal axis A when under pressure or force of bending when used insnowboarding while tip portion 430 and tail portion 432 will tend toremain rigid, the greater the resulting spring back force will be.Optionally, in order to construct differences in flexure in snowboard412, upper layer 422, under layer 424 and side layers 426 and 428 can bevaried in stiffness by varying their respective thickness and/orcomposition.

This design provides for stability and ease of turning.

The embodiments shown in FIG. 21 utilizes foam core 418 molded directlyinto its final shape, or molded nearly into the final shape. Asdescribed above, directly molding foam core 418 to its final shapeallows for a skin to form on the foam core that is not damaged by thelaminating resin. FIG. 22 shows an embodiment of the invention wherefoam core 418 has been molded and then cut to its final shape. In thisembodiment, the outer surfaces of foam core 418 is coated with sealantcoating 440 prior to upper layer 422, under layer 424 and side layers426 and 428 being affixed to foam core 418.

FIGS. 23 and 24 show snow ski 500 according to the invention, having afront portion 510, an intermediate portion 508 and a rear portion 512.The ski is provided with a binding that includes a first portion 514which is intended to co-act with the toe piece of a ski-boot and asecond portion 516 which is intended to co-act with the heel of theboot.

FIG. 25 is a cross-section through snow ski 500 of FIGS. 23 and 24. Snowski 500 includes foam core 520 completely surrounded by a skin 522 thatincludes upper layer 523, under layer 524 and side layers 526 and 528.Skin 522, as described more fully above, is bonded to cover foam core520 and includes two components, a laminating resin with optionallyadded fillers and a fabric as described above.

The density of foam core 520 can vary along the length of snow ski 500.As an example, the density of foam core 520 can be lower at frontportion 510 and rear portion 512 compared to intermediate portion 508.

The use of the present foam core 520 provides a flexible reinforcedconstruction relative to front portion 510 and rear portion 512 in thatportion of snow ski 500. This in combination with upper layer 523, underlayer 524 and side layers 526 and 528 can provide for flexure inintermediate portion of snow ski 500. As a non-limiting example, themore foam core 520 allows front portion 510 and rear portion 512 todeflect when under pressure or force of bending when used in snow ski500 while front portion 510 and rear portion 512 will tend to remainrigid, the greater the resulting spring back force will be. Optionally,in order to construct differences in flexure in snow ski 500, upperlayer 523, under layer 524 and side layers 526 and 528 can be varied instiffness by varying their respective thickness and/or composition.

This design provides for stability and ease of turning.

The embodiments shown in FIG. 25 utilizes foam core 520 molded directlyinto its final shape, or molded nearly into the final shape. Asdescribed above, directly molding foam core 520 to its final shapeallows for a skin to form on the foam core that is not damaged by thelaminating resin. FIG. 26 shows an embodiment of the invention wherefoam core 520 has been molded and then cut to its final shape. In thisembodiment, the outer surfaces of foam core 520 is coated with sealantcoating 540 prior to upper layer 523, under layer 524 and side layers526 and 528 being affixed to foam core 520.

FIGS. 27-30 generally depict a sliding device, or sled according to thepresent invention. Sled 600 typically includes elongate member 602,configured to slide on any sufficiently slippery surface, such as snow,ice, grass, metal, or water on a water slide. Often, the surface iscovered with snow or ice, and has a downward slope.

As illustrated in FIGS. 27-29, elongate member 602 includes asubstantially flat, or planar, body portion 604, and a leading endportion 606. In use, a rider sits or kneels on body portion 604. Bodyportion 604 can include one or more handgrip(s) 608, posterior toleading end portion 606 and anterior to trailing edge 610. Leading endportion 606 has an inward end that is positioned to connect to orcontinuous with forward end of body portion 604. Leading end portion 606typically extends outward from body portion 604 with an upturned shape,so as to avoid digging into the sliding surface when sled 600 movesforward.

Trailing edge 610 can be straight, can have a convex curve, or can havetwo or more convex curves, known in the art as bat tails.

FIG. 30 is a cross-section through sled 600 at elongate member 602. Sled600 includes foam core 620 completely surrounded by a skin 622 thatincludes upper layer 623, under layer 624 and side layers 626 and 628.Skin 622 as described more fully above is bonded to cover foam core 620and includes two components, a laminating resin with optionally addedfillers and a fabric as described above.

The density of foam core 620 can vary along the length of sled 600. Asan example, the density of foam core 620 can be lower at leading endportion 606 compared to body portion 604.

The use of the present foam core 620 provides a flexible reinforcedconstruction relative to leading end portion 606 and body portion 604 inthat portion of sled 600. This, in combination with upper layer 623,under layer 624 and side layers 626 and 628 can provide for flexure insled 600. As a non-limiting example, the more foam core 620 allowsleading end portion 606 to deflect when under pressure or force ofbending when used in sled 600 while body portion 604 remains rigid, thegreater the resulting spring back force will be. Optionally, in order toconstruct differences in flexure in sled 600, upper layer 623, underlayer 624 and side layers 626 and 628 can be varied in stiffness byvarying their respective thickness and/or composition.

This design provides for stability and ease of turning.

In FIG. 25 foam core 620 can be molded directly into its final shape, ormolded nearly into the final shape. As described above, directly moldingfoam core 620 to its final shape allows for a skin to form on the foamcore that is not damaged by the laminating resin. In an embodiment ofthe invention, foam core 620 can be molded and then cut to its finalshape. In this embodiment, the outer surfaces of foam core 620 arecoated with sealant coating 640 prior to upper layer 623, under layer624 and side layers 626 and 628 being affixed to foam core 620.

One or more hand grip(s) or handles 608 can be affixed to sled 600 for arider to grab onto during use. Often, sled 600 has a pair of handles 608on opposite sides of sled 600.

As described above, a blank or foam core element that includes the abovedescribed foamed and molded expandable polymer matrix is a key componentin the sports boards of the present invention. In various embodiments ofthe invention, the blank or foam core element can particularly be usedto make surfboards.

FIGS. 31 and 32 show particular, non-limiting blank or foam core elementembodiments for surfboards according to the invention. Blank 700includes lead end 702, tail end 704, rocker portion 706, and stringer708 extending from lead end 702 to tail end 704.

Lead end 702 is generally straight, perpendicular to and centered aboutstringer 708. Depending on the intended use and performancecharacteristics desired, lead end 702 can have a width 710 of from atleast about 2, in some cases at least about 2.5, and in other cases atleast about 3 inches and can be up to about 6, in some cases up to about5 and in other cases up to about 4 inches. Width 710 can be any value orrange between any of the values recited above.

Tail end 704 is generally straight, perpendicular to and centered aboutstringer 708. Depending on the intended use and performancecharacteristics desired, tail end 704 can have a width 712 of from atleast about 3, in some cases at least about 4, and in other cases atleast about 5 inches and can be up to about 12, in some cases up toabout 10 and in other cases up to about 9 inches. Width 712 can be anyvalue or range between any of the values recited above.

Depending on the intended use and performance characteristics desired,blank 700 can have a length 714 measured from lead end 710 to tail end712 of from at least about 4, in some cases at least about 5, and inother cases at least about 6 feet and can be up to 10, in some cases upto about 9 and in other cases up to about 8 feet. Length 714 can be anyvalue or range between any of the values recited above.

Rocker portion 706 of blank 700 generally curves upwards from a bottomsurface of blank 700. Rocker portion 706 makes up the portion of blank700 near lead end 702 and can be characterized in terms of what portionof length 714 curves upwardly to form rocker portion 706. The size ofrocker portion 708 will vary depending on the intended use andperformance characteristics desired in surfboards made from blank 700.Typically, rocker portion 706, can include at least the lead 10% oflength 714, in some cases at least the lead 15% of length 714, and inother cases at least the lead 20% of length 714 and can be up to thelead 50% of length 714, in some cases up to the lead 40% of length 714,and in other cases up to the lead 30% of length 714. Rocker portion 706of blank 700 can be any value or range between any of the values recitedabove.

Rocker portion 706 of blank 700 can be characterized by the amount theupward curve departs from the bottom surface of blank 700 (deflection718). Deflection 718 represents the vertical distance from the plane ofthe bottom surface of blank 700 to lead end 702. The length ofdeflection 718 in rocker portion 708 will vary depending on the intendeduse and performance characteristics desired in surfboards made fromblank 700. Deflection 718 can be at least about 3 inches, in some casesat least about 4 inches and in other cases at least about 4.5 inches andcan be up to about 10 inches, in some cases at least about 8 inches, andin other cases at least about 6 inches. The length of deflection 718 canbe any value or range between any of the values recited above.

Stringer 708 extends from tail end 704 to lead end 702 of blank 700 andis positioned between first portion 720 and second portion 722 of blank700. Stringer 708 generally corresponds to the shape and curvature ofblank 700, and in particular to rocker portion 706.

In many aspects of this embodiment, first portion 720 and second portion722 are approximately equivalent in size, shape, weight and dimension.As indicated above, stringer 708 can be made of wood, carbon/graphitereinforced material, composite material, metal and/or combinations ofsuch materials. Stringer 708 can be incorporated into blank 700 bycutting a molded plank of the expanded polymer matrix into two parts,first portion 720 and second portion 722, and subsequently using anappropriate adhesive to attaché first portion 720 and second portion 722to opposing sides of stringer 708. Alternatively, expansion holes can beplaced through stringer 718 and then be placed in a mold for moldingblank 700 as described above. During the molding/bead expansion process,the expandable polymer matrix prepuff expands and fuses, in particular,expanding through the expansion holes to provide a one piece blank offirst portion 720, stringer 708 and second portion 722.

The width and composition of stringer 708 are selected to providedesirable combinations of stiffness, response and flexibility. As such,the width of stringer 708, measured as the distance between firstportion 720 and second portion 722, can be at least about 0.1 inches, insome cases at least about 0.2 inches and in other cases at least about0.25 inches and can be up to about 2 inches, in some cases up to about1.5 inches and in other cases up to about 1 inch. The width of stringer708 can be any value or range between any of the values recited above.

FIGS. 33 and 34 show additional particular, non-limiting blank or foamcore element embodiments for surfboards according to the invention.Blank 750 includes lead end 752, tail end 754, rocker portion 756, andstringer 758 extending from lead end 752 to tail end 754.

Lead end 752 is generally straight, perpendicular to and centered aboutstringer 758 and curves into the sides of blank 750. Depending on theintended use and performance characteristics desired, lead end 752 canhave a width 760 of from at least about 1, in some cases at least about1.5, and in other cases at least about 2 inches and can be up to about5, in some cases up to about 4.5 and in other cases up to about 4inches. Width 760 can be any value or range between any of the valuesrecited above.

Tail end 754 is generally straight, perpendicular to and centered aboutstringer 758 and curves into the sides of blank 750. Depending on theintended use and performance characteristics desired, tail end 754 canhave a width 762 of from at least about 4, in some cases at least about5, and in other cases at least about 6 inches and can be up to about 14,in some cases up to about 12 and in other cases up to about 11 inches.Width 762 can be any value or range between any of the values recitedabove.

Depending on the intended use and performance characteristics desired,blank 750 can have a length 764 measured from lead end 752 to tail end754 of from at least about 4, in some cases at least about 5, and inother cases at least about 6 feet and can be up to 10, in some cases upto about 9 and in other cases up to about 8 feet. Length 764 can be anyvalue or range between any of the values recited above.

Rocker portion 756 of blank 750 generally curves upwards from a bottomsurface of blank 750. Rocker portion 756 makes up the portion of blank750 near lead end 752 and can be characterized in terms of what portionof length 764 curves upwardly to form rocker portion 756. The size ofrocker portion 758 will vary depending on the intended use andperformance characteristics desired in surfboards made from blank 750.Typically, rocker portion 756, can include at least the lead 10% oflength 764, in some cases at least the lead 12.5% of length 764, and inother cases at least the lead 15% of length 764 and can be up to thelead 40% of length 764, in some cases up to the lead 30% of length 764,and in other cases up to the lead 25% of length 764. Rocker portion 756of blank 750 can be any value or range between any of the values recitedabove.

Rocker portion 756 of blank 750 can be characterized by the amount theupward curve departs from the bottom surface of blank 750 (deflection768). Deflection 768 represents the vertical distance from the plane ofthe bottom surface of blank 750 to lead end 752. The length ofdeflection 768 in rocker portion 758 will vary depending on the intendeduse and performance characteristics desired in surfboards made fromblank 750. Deflection 768 can be at least about 2 inches, in some casesat least about 2.5 inches and in other cases at least about 3 inches andcan be up to about 8 inches, in some cases at least about 7 inches, andin other cases at least about 6 inches. The length of deflection 768 canbe any value or range between any of the values recited above.

Stringer 758 extends from tail end 754 to lead end 752 of blank 750 andis positioned between first portion 770 and second portion 772 of blank750. Stringer 758 generally corresponds to the shape and curvature ofblank 750, and in particular to rocker portion 756.

In many aspects of this embodiment, first portion 770 and second portion772 are approximately equivalent in size, shape, weight and dimension.

Stringer 758 can be made of materials as described above, bedimensionally similar to and incorporated into blank 750 using themethods described in relation to blank 700.

FIGS. 35 and 36 show further particular, non-limiting blank or foam coreelement embodiments for surfboards according to the invention. Blank 800includes lead end 802, tail end 804, rocker portion 806, and stringer808 extending from lead end 802 to tail end 804.

Lead end 802 is generally straight, perpendicular to and centered aboutstringer 808 and curves into the sides of blank 800. Depending on theintended use and performance characteristics desired, lead end 802 canhave a width 810 of from at least about 3, in some cases at least about4, and in other cases at least about 5 inches and can be up to about 10,in some cases up to about 9 and in other cases up to about 8 inches.Width 810 can be any value or range between any of the values recitedabove.

Tail end 804 is generally straight, perpendicular to and centered aboutstringer 808 and curves into the sides of blank 800. Depending on theintended use and performance characteristics desired, tail end 804 canhave a width 812 of from at least about 4, in some cases at least about6, and in other cases at least about 8 inches and can be up to about 20,in some cases up to about 18 and in other cases up to about 16 inches.Width 812 can be any value or range between any of the values recitedabove.

Depending on the intended use and performance characteristics desired,blank 800 can have a length 814 measured from lead end 802 to tail end804 of from at least about 4, in some cases at least about 5, and inother cases at least about 6 feet and can be up to 10, in some cases upto about 9 and in other cases up to about 8 feet. Length 814 can be anyvalue or range between any of the values recited above.

Rocker portion 806 of blank 800 generally curves upwards from a bottomsurface of blank 800. Rocker portion 806 makes up the portion of blank800 near lead end 802 and can be characterized in terms of what portionof length 814 curves upwardly to form rocker portion 806. The size ofrocker portion 808 will vary depending on the intended use andperformance characteristics desired in surfboards made from blank 800.Typically, rocker portion 806, can include at least the lead 10% oflength 814, in some cases at least the lead 12.5% of length 814, and inother cases at least the lead 15% of length 814 and can be up to thelead 40% of length 814, in some cases up to the lead 30% of length 814,and in other cases up to the lead 25% of length 814. Rocker portion 806of blank 800 can be any value or range between any of the values recitedabove.

Rocker portion 806 of blank 800 can be characterized by the amount theupward curve departs from the bottom surface of blank 800 (deflection818). Deflection 818 represents the vertical distance from the plane ofthe bottom surface of blank 800 to lead end 802. The length ofdeflection 818 in rocker portion 808 will vary depending on the intendeduse and performance characteristics desired in surfboards made fromblank 800. Deflection 818 can be at least about 2 inches, in some casesat least about 2.5 inches and in other cases at least about 3 inches andcan be up to about 9 inches, in some cases at least about 8 inches, andin other cases at least about 7 inches. The length of deflection 818 canbe any value or range between any of the values recited above.

Stringer 808 extends from tail end 804 to lead end 802 of blank 800 andis positioned between first portion 820 and second portion 822 of blank800. Stringer 808 generally corresponds to the shape and curvature ofblank 800, and in particular to rocker portion 806.

In many aspects of this embodiment, first portion 820 and second portion822 are approximately equivalent in size, shape, weight and dimension.

Stringer 808 can be made of materials as described above, bedimensionally similar to and incorporated into blank 800 using themethods described in relation to blank 700.

In embodiments of the invention, surfboards made according to theinvention using the cores or blanks described in FIGS. 31-36 can bedeflected using the Emerson 8510 compression tester apparatus asdescribed 0.75 inches (1.9 cm), in some cases 0.79 inches (2 cm) and inparticular instances 0.83 inches (2.1 cm) without demonstrating adeflection in the stress—strain curve. Additionally, the presentsurfboards do not fail when deflected 0.87 inches (2.2 cm), in somecases 0.91 inches (2.3 cm) and in particular instances 0.94 inches (2.4cm). After, such deflections, the present surfboards are able to returnto their original shape. The particular properties of a particular boardwill depend on the composition of the blank or core and laminating resinused to glass the surfboard.

Further, even after failure of the present surfboards using the Emerson8510 compression tester apparatus as described above, the presentsurfboards are able to support a load of at least 100 pounds (45.4 kg),in some cases at least 150 pounds (68 kg) and in other cases at least200 pounds (91 kg). The particular properties of a particular board willdepend on the composition of the blank or core and laminating resin usedto glass the surfboard.

Because the sports boards of the present invention are made from theabove-described expanded polymer matrix, they are generally lighter inweight than conventional sports boards, but can be handled in the sameway because of the physical characteristics of the foam core and sportsboards as described above. As such, the present sports boards areideally suited for use in various sporting activities.

Various embodiments and structures have been described herein, which arenot meant to be limiting to one application. Various designs andstructures of one type of sports board can be incorporated into othertypes of sports boards to obtain desired characteristics as thoseskilled in the art will readily appreciate.

The present invention will further be described by reference to thefollowing examples. The following examples are merely illustrative ofthe invention and are not intended to be limiting.

Example 1

This example demonstrates the superior flexibility of surfboards madeaccording to the invention.

Test Apparatus

Testing was conducted on an Emerson 8510 compression tester, (EmersonApparatus Company, Inc., Portland, Me.), designed in accordance with therequirements of ASTM D642 and TAPPI T804 equipment specifications. Theprogrammable platen was set at a rate of 0.5 inches (1.27 cm) perminute. The fixture used was a modified design of the general testprotocol for alpine skis, a three point bending test to ASTM Standard780-93a.

Each surfboard was placed on the fixture, which was installed under theEmerson apparatus aligned to the same center point. The base of eachsurfboard was supported by a 1.5″ diameter free floating steel rod so asto not apply any friction to the base of the board as it was beingdeflected from the top. The spacing between the bottom rails is 28inches and the selection of the spacing was determined through findingsof the major compression points from the tail and lead end typicallyfound while surfing.

The upper force fixture placed a downward force on the center of thesurfboard as measured 38 inches form the lead end of the surfboard. Thelaminated structure included a rubber compliant fixture (19 incheslong×1.5 inches wide) that followed the contour of the surfboard deck soas to apply an equal amount of force across the width of the surfboard.

Sample Description

The sample surfboards were similar to those shown in FIGS. 31 and 32,approximately 70 inches (178 cm) long. The blanks for each sample weremolded, and cut in half lengthwise and a wooden stringer attached toeach half with an adhesive. The blanks were glassed using a polyesterlaminate. All ingredients and construction were identical except for thefoam material for the blanks, which were as follows:

-   -   Sample 1: 2.5 lb/ft³ (40 kg/m³) density polyurethane    -   Sample 2: 2.5 lb/ft³ (40 kg/m³) density expanded ARCEL® 730        resin (NOVA Chemicals Inc., Pittsburgh, Pa.)

Each surfboard was placed on the test apparatus and the platen waslowered until a break in the stress-strain curve indicated a failure.Sample 1 indicated a failure at 0.71 inches (1.8 cm) of deflection andsample 2 at 0.79 inches (2.0 cm) of deflection.

The performance of the foam crushing after the structural failure ofeach surfboard was evident in the formation of a downward trend in thestress—strain curve. The compressive set observed in samples 1 was muchlower than that of sample 2, the foam in which appeared to store adegree of latent energy during compression.

The data demonstrate the superior flexibility of the surfboard madeaccording to the invention.

Example 2

This example demonstrates the superior flexibility of surfboards madeaccording to the invention. The test apparatus described in Example 1was also used in this Example.

Sample Description

The sample surfboards were similar to those shown in FIGS. 31 and 32,approximately 70 inches (178 cm) long. The blanks for each sample weremolded, and cut in half lengthwise and a wooden stringer attached toeach half with an adhesive. The blanks were glassed using an epoxylaminate. All ingredients and construction were identical except for thefoam material for the blanks, which were as follows:

-   -   Sample 3: 2.5 lb/ft³ (40 kg/m³) density expanded polystyrene    -   Sample 4: 2.5 lb/ft³ (40 kg/m³) density expanded ARCEL® 730        resin

Each surfboard was placed on the test apparatus and the platen waslowered until a break in the stress-strain curve indicated a failure.Sample 3 indicated a failure at 0.71 inches (1.8 cm) and sample 4 at0.85 inches (2.2 cm) of deflection.

The performance of the foam crushing after the structural failure ofeach surfboard was evident in the formation of a downward trend in thestress—strain curve. The compressive set observed in samples 3 was muchlower than that of sample 4, the foam in which appeared to store adegree of latent energy during compression.

The data demonstrate the superior flexibility of the surfboard madeaccording to the invention.

Example 3

This example demonstrates the effect of laminate on the flexibility ofsurfboards made according to the invention. The test apparatus describedin Example 1 was also used in this Example.

The sample surfboards were similar to those shown in FIGS. 31 and 32,approximately 70 inches (178 cm) long. The blanks for each sample weremolded, and cut in half lengthwise and a wooden stringer attached toeach half with an adhesive. The foam used for the blanks was 2.5 lb/ft³(40 kg/m³) density expanded ARCEL® 730 resin. All ingredients andconstruction were identical except for the laminate resin used to glassthe blanks, which were as follows:

-   -   Sample 5: blank glassed using an epoxy laminate    -   Sample 6: blank glassed using a polyester laminate

Each surfboard was placed on the test apparatus and the platen waslowered at a rate of 0.5 inches (1.27 cm) per minute to a deflection of1 inch (2.54 cm). The deflection and load where a break in thestress-strain curve was noted as a deflection point. The deflectionpoint for sample 5 was 0.85 inches (2.2 cm) at a load of 886 lb. (402kg) and for sample 6 was 0.79 inches (2.0 cm) at a load of 728 lb. (330kg).

The test above was repeated on the same boards, except the platen waslowered at a rate of 0.5 inches (1.27 cm) per minute to a deflection of1.5 inches (3.8 cm). The deflection and load where a break in thestress-strain curve was again noted as a deflection point. Thedeflection point for sample 5 was 0.99 inches (2.5 cm) at a load of 687lb. (312 kg) and for sample 6 was 0.95 inches (2.4 cm) at a load of 525lb. (238 kg). Although both surfboards exhibited a deflection point,complete failure was not observed and the foam blank of each surfboardcontinued to support a load at the 1.5 inches (3.8 cm) deflection, 510lb. (231 kg) for sample 5 and 490 lb. (222 kg) for sample 6.

A comparable test with the polyurethane surfboard of sample 1demonstrated complete failure and no load support at 1.2 inches (3 cm)deflection. A comparable test with the expanded polystyrene surfboard ofsample 3 demonstrated complete failure and no load support at 1.35inches (3.4 cm) deflection.

A 2 inch (5 cm) diameter plug with a rounded top was engineered andfastened to a rigid base to support the plug. This fixture was attachedwith clamps to the upper moving platen of the Emerson compressiontester. The face plate of the test fixture was driven downward at a rateof 0.5 inches (1.27 cm) per minute. The base of each surfboard wasaffixed to a solid steel table placed under the moving platen.

The outer skin of the sample 4 (epoxy laminate) provided a more durableshell demonstrating a peak load at 430 pounds (190 kg) with a peakdeflection at 0.0456 inches (0.12 cm). Sample 5 demonstrated a peak loadof 245 pounds (111 kg) at a crack deflection of 0.315 inches (0.8 cm).

The data demonstrate the toughness and durability properties ofsurfboards made according to the present invention and also highlightthe improved safety features of such a board, as a safe degree ofintegrity is maintained even under conditions where prior art surfboardsfail catastrophically.

The present invention has been described with reference to specificdetails of particular embodiments thereof. It is not intended that suchdetails be regarded as limitations upon the scope of the inventionexcept insofar as and to the extent that they are included in theaccompanying claims.

1-25. (canceled)
 26. A method of making a surfboard comprising: a)producing interpolymer particles of a polyolefin and in situ polymerizedvinyl aromatic monomers by suspending polyolefin particles and vinylaromatic monomers in an aqueous suspension and polymerizing the monomersinside the polyolefin particles; b) producing expandable interpolymerparticles by impregnating the interpolymer particles with a blowingagent and optionally a plasticizer; c) expanding and molding theexpandable interpolymer particles into a foam core shape, having anupper surface and an under surface, by applying steam to expand theparticles and cause fusion between the particles; d) optionally applyinga sealant to the upper surface or under surface; and e) applying anupper layer covering to at least a portion of the upper surface orapplying an under layer covering to at least a portion of the undersurface; wherein the interpolymer particles comprise from 20% to 80% byweight of the polyolefin and 20% to 80% by weight of the polymerizedvinyl aromatic monomers.
 27. The method according to claim 26, whereinthe foam core part comprises expanded and fused interpolymer particleswith a skin formed on at least a portion of the upper surface or theunder surface.
 28. The method according to claim 26, wherein the vinylaromatic monomers comprise styrene.
 29. The method according to claim26, wherein the polyolefin particles comprise polymers selected from thegroup consisting of polypropylene, polyethylene, ethylene vinyl acetatecopolymer; ethylene/propylene copolymer; blends of polyethylene andpolypropylene; blends of polyethylene and an ethylene/vinyl acetatecopolymer; blends of polyethylene and an ethylene/propylene copolymer,ethylene-butyl acrylate copolymer and ethylene-methyl methacrylatecopolymer.
 30. The method according to claim 26, wherein the blowingagent is selected from the group consisting of butanes, pentanes,hexanes, and halogenated hydrocarbons.
 31. The method according to claim26, wherein the plasticizer is selected from the group consisting ofbenzene, toluene, limonene, linear, branched or cyclic C₅ to C₂₀alkanes, white oil, linear, branched or cyclic C₁ to C₂₀dialkylphthalates, styrene, oligomers of styrene, oligomers of(meth)acrylates having a glass transition temperature less thanpolystyrene, and combinations thereof.
 32. The method according to claim26, comprising: b-1) pre-expanding the expandable interpolymer particlesto form pre-expanded interpolymer particles; and b-2) ageing thepre-expanded interpolymer particles for four to 48 hours.
 33. The methodaccording to claim 26, wherein the expanding and molding the expandableinterpolymer particles into a foam core shape is carried out in a steammolding press.
 34. The method according to claim 26, wherein the sealantagent is selected from the group consisting of ethylene-vinyl acetatecopolymers, ethylene-vinyl alcohol copolymers, ethylene-acrylic acidcopolymers, styrene-butadiene polymers, styrene-isoprene polymers,styrene-butadiene-styrene block polymers, styrene-isoprene-styrene blockpolymers, hydrogenated resins thereof, joint compound, gypsum paste,polyurethanes, polypropylene, and polyethylene.
 35. The method accordingto claim 26, wherein the sealant comprises a thermoplastic polyolefin; athermoplastic styrenic polymer; and a styrenic block copolymer.
 36. Themethod according to claim 26, wherein the upper layer covering or underlayer covering comprises fibrous mats or fibrous fabric.
 37. The methodaccording to claim 36, wherein the fibrous mats or fibrous fabriccomprise fibers selected from the group consisting of glass fibers,aramide fibers, polyamide fibers, carbon fibers, silicon carbide fibers,composite fibers, metal fibers, fiberglass, and combinations thereof.38. The method according to claim 26, comprising: e-1) applying one ormore fibrous layers to the upper surface or the under surface a of thefoam core shape; e-2) applying a laminating resin to the one or morefibrous layers; e-3) curing the laminating resin such that it is allowedto cure and harden, securing the one or more fibrous layers to the foamcore shape.
 39. The method according to claim 38, wherein the laminatingresin comprises a resin system, a cure catalyst, and optionally fillermaterials.
 40. The method according to claim 39, wherein the laminatingresin comprises a resin selected from the group consisting ofunsaturated polyester resins, saturated polyester resins, epoxy resins,phenol-formaldehyde resins, melamine-formaldehyde resins,urea-formaldehyde resins, unsaturated polyesteramide resins, vinyl esterresins, polyimide resins, poly amide-imide resins, unsaturated(meth)acrylic resins, and acrylic-urethane resins.
 41. The methodaccording to claim 26, comprising: e-1) applying one or more fibrouslayers to the upper surface or the under surface a of the foam coreshape; e-2) applying a laminating resin to the one or more fibrouslayers to provide a treated foam core shape; e-3) inserting the treatedfoam core shape into a lower mold segment of a mold press; e-4) closingthe mold press; e-5) applying pressure in the mold press to cause thelaminating resin to be completely distributed in the space between thefoam core and the one or more fibrous layers; e-6) curing the treatedfoam core shape to provide a closed fiber-reinforced shell in intimatecontact with the foam core shape.
 42. The method according to claim 41,wherein the laminating resin comprises a resin system, a cure catalyst,and optionally filler materials.
 43. The method according to claim 42,wherein the laminating resin comprises a resin selected from the groupconsisting of unsaturated polyester resins, saturated polyester resins,epoxy resins, phenol-formaldehyde resins, melamine-formaldehyde resins,urea-formaldehyde resins, unsaturated polyesteramide resins, vinyl esterresins, polyimide resins, poly amide-imide resins, unsaturated(meth)acrylic resins, and acrylic-urethane resins.
 44. The methodaccording to claim 26, wherein the foam core shape has a flexuralstrength at 5% strain of at least 60 psi at a molded density of about2.25 lb/ft³.
 45. The method according to claim 26, wherein the foam coreshape has a tensile strength of at least 75 psi at a molded density ofabout 2.25 lb/ft³.
 46. The method according to claim 26, wherein theupper layer covering or under layer covering comprise one or morepolyolefins.
 47. The method according to claim 26, wherein the foam coreshape comprises one or more axial or parabolic stringers.
 48. The methodaccording to claim 26, wherein the surfboard comprises one or more finssecured to and extending from the under layer covering.
 49. The methodaccording to claim 26, wherein the foam core part has a water absorptionof less than 2 volume percent.
 50. A surfboard board made according tothe method of claim 26.